Dec 30, 2023 · Dec 31, 2023 · Dec 31, 2023 · Jan 2, 2024 · Jan 2, 2024 · Jan 2, 2024
diff --git a/Makefile b/Makefile
@@ -53,7 +53,7 @@ DATAFORM=		main
 
 LOCALTIME=	Factory
 
-# The POSIXRULES macro controls interpretation of POSIX-like TZ
+# The POSIXRULES macro controls interpretation of POSIX-2017.1-like TZ
 # settings like TZ='EET-2EEST' that lack DST transition rules.
 # If POSIXRULES is '-', no template is installed; this is the default.
 # Any other value for POSIXRULES is obsolete and should not be relied on, as:
@@ -274,7 +274,7 @@ LDLIBS=
 #  -DTZ_DOMAINDIR=\"/path\" to use "/path" for gettext directory;
 #	the default is system-supplied, typically "/usr/lib/locale"
 #  -DTZDEFRULESTRING=\",date/time,date/time\" to default to the specified
-#	DST transitions for POSIX-style TZ strings lacking them,
+#	DST transitions for POSIX.1-2017-style TZ strings lacking them,
 #	in the usual case where POSIXRULES is '-'.  If not specified,
 #	TZDEFRULESTRING defaults to US rules for future DST transitions.
 #	This mishandles some past timestamps, as US DST rules have changed.
@@ -340,9 +340,10 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
 # guess TM_GMTOFF from other macros; define NO_TM_GMTOFF to suppress this.
 # Similarly, if your system has a "zone abbreviation" field, define
 #	-DTM_ZONE=tm_zone
-# and define NO_TM_ZONE to suppress any guessing.  Although these two fields
-# not required by POSIX, a future version of POSIX is planned to require them
-# and they are widely available on GNU/Linux and BSD systems.
+# and define NO_TM_ZONE to suppress any guessing.
+# Although these two fields are not required by POSIX.1-2017,
+# POSIX 202x/D4 requires them and they are widely available
+# on GNU/Linux and BSD systems.
 #
 # The next batch of options control support for external variables
 # exported by tzcode.  In practice these variables are less useful
@@ -352,7 +353,7 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
 # #	-DHAVE_TZNAME=0 # do not support "tzname"
 # #	-DHAVE_TZNAME=1 # support "tzname", which is defined by system library
 # #	-DHAVE_TZNAME=2 # support and define "tzname"
-# # to the "CFLAGS=" line.  "tzname" is required by POSIX 1988 and later.
+# # to the "CFLAGS=" line.  "tzname" is required by POSIX.1-1988 and later.
 # # If not defined, the code attempts to guess HAVE_TZNAME from other macros.
 # # Warning: unless time_tz is also defined, HAVE_TZNAME=1 can cause
 # # crashes when combined with some platforms' standard libraries,
@@ -362,8 +363,8 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
 # #	-DUSG_COMPAT=0 # do not support
 # #	-DUSG_COMPAT=1 # support, and variables are defined by system library
 # #	-DUSG_COMPAT=2 # support and define variables
-# # to the "CFLAGS=" line; "timezone" and "daylight" are inspired by
-# # Unix Systems Group code and are required by POSIX 2008 (with XSI) and later.
+# # to the "CFLAGS=" line; "timezone" and "daylight" are inspired by Unix
+# # Systems Group code and are required by POSIX.1-2008 and later (with XSI).
 # # If not defined, the code attempts to guess USG_COMPAT from other macros.
 # #
 # # To support the external variable "altzone", add
@@ -427,7 +428,7 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
 
 # The name of a POSIX-like library archiver, its flags, C compiler,
 # linker flags, and 'make' utility.  Ordinarily the defaults suffice.
-# The commented-out values are the defaults specified by POSIX 202x/D3.
+# The commented-out values are the defaults specified by POSIX.1-202x/D4.
 #AR = ar
 #ARFLAGS = -rv
 #CC = c17
@@ -439,6 +440,12 @@ GCC_DEBUG_FLAGS = -DGCC_LINT -g3 -O3 -fno-common \
 
 LEAPSECONDS=
 
+# Where to fetch leap-seconds.list from.
+leaplist_URI = \
+  https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list
+# The file is generated by the IERS Earth Orientation Centre, in Paris.
+leaplist_TZ = Europe/Paris
+
 # The zic command and its arguments.
 
 zic=		./zic
@@ -471,7 +478,8 @@ AWK=		awk
 # is typically nicer if it works.
 KSHELL=		/bin/bash
 
-# Name of curl <https://curl.haxx.se/>, used for HTML validation.
+# Name of curl <https://curl.haxx.se/>, used for HTML validation
+# and to fetch leap-seconds.list from upstream.
 CURL=		curl
 
 # Name of GNU Privacy Guard <https://gnupg.org/>, used to sign distributions.
@@ -718,6 +726,28 @@ leapseconds:	$(LEAP_DEPS)
 		  -f leapseconds.awk leap-seconds.list >$@.out
 		mv $@.out $@
 
+# Awk script to extract a Git-style author from leap-seconds.list comments.
+EXTRACT_AUTHOR = \
+  author_line { sub(/^.[[:space:]]*/, ""); \
+      sub(/:[[:space:]]*/, " <"); \
+      printf "%s>\n", $$0; \
+      success = 1; \
+      exit \
+  } \
+  /Questions or comments to:/ { author_line = 1 } \
+  END { exit !success }
+
+# Fetch leap-seconds.list from upstream.
+fetch-leap-seconds.list:
+		$(CURL) -OR $(leaplist_URI)
+
+# Fetch leap-seconds.list from upstream and commit it to the local repository.
+commit-leap-seconds.list: fetch-leap-seconds.list
+		author=$$($(AWK) '$(EXTRACT_AUTHOR)' leap-seconds.list) && \
+		date=$$(TZ=$(leaplist_TZ) stat -c%y leap-seconds.list) && \
+		git commit --author="$$author" --date="$$date" -m'make $@' \
+		  leap-seconds.list
+
 # Arguments to pass to submakes of install_data.
 # They can be overridden by later submake arguments.
 INSTALLARGS = \
@@ -1315,7 +1345,8 @@ zic.o:		private.h tzfile.h tzdir.h version.h
 .PHONY: ALL INSTALL all
 .PHONY: check check_mild check_time_t_alternatives
 .PHONY: check_web check_zishrink
-.PHONY: clean clean_misc dummy.zd force_tzs
+.PHONY: clean clean_misc commit-leap-seconds.list dummy.zd
+.PHONY: fetch-leap-seconds.list force_tzs
 .PHONY: install install_data maintainer-clean names
 .PHONY: posix_only posix_right public
 .PHONY: rearguard_signatures rearguard_signatures_version

diff --git a/NEWS b/NEWS
@@ -1,5 +1,73 @@
 News for the tz database
 
+Release 2024a - 2024-02-01 09:28:56 -0800
+
+  Briefly:
+    Kazakhstan unifies on UTC+5 beginning 2024-03-01.
+    Palestine springs forward a week later after Ramadan.
+    zic no longer pretends to support indefinite-past DST.
+    localtime no longer mishandles Ciudad Juárez in 2422.
+
+  Changes to future timestamps
+
+    Kazakhstan unifies on UTC+5.  This affects Asia/Almaty and
+    Asia/Qostanay which together represent the eastern portion of the
+    country that will transition from UTC+6 on 2024-03-01 at 00:00 to
+    join the western portion.  (Thanks to Zhanbolat Raimbekov.)
+
+    Palestine springs forward a week later than previously predicted
+    in 2024 and 2025.  (Thanks to Heba Hamad.)  Change spring-forward
+    predictions to the second Saturday after Ramadan, not the first;
+    this also affects other predictions starting in 2039.
+
+  Changes to past timestamps
+
+    Asia/Ho_Chi_Minh's 1955-07-01 transition occurred at 01:00
+    not 00:00.  (Thanks to Đoàn Trần Công Danh.)
+
+    From 1947 through 1949, Toronto's transitions occurred at 02:00
+    not 00:00.  (Thanks to Chris Walton.)
+
+    In 1911 Miquelon adopted standard time on June 15, not May 15.
+
+  Changes to code
+
+    The FROM and TO columns of Rule lines can no longer be "minimum"
+    or an abbreviation of "minimum", because TZif files do not support
+    DST rules that extend into the indefinite past - although these
+    rules were supported when TZif files had only 32-bit data, this
+    stopped working when 64-bit TZif files were introduced in 1995.
+    This should not be a problem for realistic data, since DST was
+    first used in the 20th century.  As a transition aid, FROM columns
+    like "minimum" are now diagnosed and then treated as if they were
+    the year 1900; this should suffice for TZif files on old systems
+    with only 32-bit time_t, and it is more compatible with bugs in
+    2023c-and-earlier localtime.c.  (Problem reported by Yoshito
+    Umaoka.)
+
+    localtime and related functions no longer mishandle some
+    timestamps that occur about 400 years after a switch to a time
+    zone with a DST schedule.  In 2023d data this problem was visible
+    for some timestamps in November 2422, November 2822, etc. in
+    America/Ciudad_Juarez.  (Problem reported by Gilmore Davidson.)
+
+    strftime %s now uses tm_gmtoff if available.  (Problem and draft
+    patch reported by Dag-Erling Smørgrav.)
+
+  Changes to build procedure
+
+    The leap-seconds.list file is now copied from the IERS instead of
+    from its downstream counterpart at NIST, as the IERS version is
+    now in the public domain too and tends to be more up-to-date.
+    (Thanks to Martin Burnicki for liaisoning with the IERS.)
+
+  Changes to documentation
+
+    The strftime man page documents which struct tm members affect
+    which conversion specs, and that tzset is called.  (Problems
+    reported by Robert Elz and Steve Summit.)
+
+
 Release 2023d - 2023-12-21 20:02:24 -0800
 
   Briefly:

diff --git a/africa b/africa
@@ -30,6 +30,10 @@
 # Milne J. Civil time. Geogr J. 1899 Feb;13(2):173-94.
 # https://www.jstor.org/stable/1774359
 #
+# For the 1911/1912 establishment of standard time in French possessions, see:
+# Société Française de Physique, Recueil de constantes physiques (1913),
+# page 752, 18b.
+#
 # European-style abbreviations are commonly used along the Mediterranean.
 # For sub-Saharan Africa abbreviations were less standardized.
 # Previous editions of this database used WAT, CAT, SAT, and EAT
@@ -113,7 +117,7 @@ Zone Atlantic/Cape_Verde -1:34:04 -	LMT	1912 Jan 01  2:00u # Praia
 
 # Chad
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Africa/Ndjamena	1:00:12 -	LMT	1912        # N'Djamena
+Zone	Africa/Ndjamena	1:00:12 -	LMT	1912 Jan  1 # N'Djamena
 			1:00	-	WAT	1979 Oct 14
 			1:00	1:00	WAST	1980 Mar  8
 			1:00	-	WAT
@@ -139,7 +143,7 @@ Zone	Africa/Ndjamena	1:00:12 -	LMT	1912        # N'Djamena
 #	Inaccessible, Nightingale: uninhabited
 
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Africa/Abidjan	-0:16:08 -	LMT	1912
+Zone	Africa/Abidjan	-0:16:08 -	LMT	1912 Jan  1
 			 0:00	-	GMT
 
 ###############################################################################

diff --git a/asia b/asia
@@ -2457,18 +2457,33 @@ Zone	Asia/Amman	2:23:44 -	LMT	1931
 # effective December 21st, 2018....
 # http://adilet.zan.kz/rus/docs/P1800000817 (russian language).
 
+# From Zhanbolat Raimbekov (2024-01-19):
+# Kazakhstan (all parts) switching to UTC+5 on March 1, 2024
+# https://www.gov.kz/memleket/entities/mti/press/news/details/688998?lang=ru
+# [in Russian]
+# (2024-01-20): https://primeminister.kz/ru/decisions/19012024-20
+#
+# From Alexander Krivenyshev (2024-01-19):
+# According to a different news and the official web site for the Ministry of
+# Trade and Integration of the Republic of Kazakhstan:
+# https://en.inform.kz/news/kazakhstan-to-switch-to-single-hour-zone-mar-1-54ad0b/
+
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 #
 # Almaty (formerly Alma-Ata), representing most locations in Kazakhstan
-# This includes KZ-AKM, KZ-ALA, KZ-ALM, KZ-AST, KZ-BAY, KZ-VOS, KZ-ZHA,
-# KZ-KAR, KZ-SEV, KZ-PAV, and KZ-YUZ.
+# This includes Abai/Abay (ISO 3166-2 code KZ-10), Aqmola/Akmola (KZ-11),
+# Almaty (KZ-19), Almaty city (KZ-75), Astana city (KZ-71),
+# East Kazkhstan (KZ-63), Jambyl/Zhambyl (KZ-31), Jetisu/Zhetysu (KZ-33),
+# Karaganda (KZ-35), North Kazakhstan (KZ-59), Pavlodar (KZ-55),
+# Shyumkent city (KZ-79), Turkistan (KZ-61), and Ulytau (KZ-62).
 Zone	Asia/Almaty	5:07:48 -	LMT	1924 May  2 # or Alma-Ata
 			5:00	-	+05	1930 Jun 21
 			6:00 RussiaAsia +06/+07	1991 Mar 31  2:00s
 			5:00 RussiaAsia	+05/+06	1992 Jan 19  2:00s
 			6:00 RussiaAsia	+06/+07	2004 Oct 31  2:00s
-			6:00	-	+06
-# Qyzylorda (aka Kyzylorda, Kizilorda, Kzyl-Orda, etc.) (KZ-KZY)
+			6:00	-	+06	2024 Mar  1  0:00
+			5:00	-	+05
+# Qyzylorda (aka Kyzylorda, Kizilorda, Kzyl-Orda, etc.) (KZ-43)
 Zone	Asia/Qyzylorda	4:21:52 -	LMT	1924 May  2
 			4:00	-	+04	1930 Jun 21
 			5:00	-	+05	1981 Apr  1
@@ -2481,8 +2496,7 @@ Zone	Asia/Qyzylorda	4:21:52 -	LMT	1924 May  2
 			5:00 RussiaAsia	+05/+06	2004 Oct 31  2:00s
 			6:00	-	+06	2018 Dec 21  0:00
 			5:00	-	+05
-#
-# Qostanay (aka Kostanay, Kustanay) (KZ-KUS)
+# Qostanay (aka Kostanay, Kustanay) (KZ-39)
 # The 1991/2 rules are unclear partly because of the 1997 Turgai
 # reorganization.
 Zone	Asia/Qostanay	4:14:28 -	LMT	1924 May  2
@@ -2493,9 +2507,9 @@ Zone	Asia/Qostanay	4:14:28 -	LMT	1924 May  2
 			5:00 RussiaAsia	+05/+06	1991 Mar 31  2:00s
 			4:00 RussiaAsia	+04/+05	1992 Jan 19  2:00s
 			5:00 RussiaAsia	+05/+06	2004 Oct 31  2:00s
-			6:00	-	+06
-
-# Aqtöbe (aka Aktobe, formerly Aktyubinsk) (KZ-AKT)
+			6:00	-	+06	2024 Mar  1  0:00
+			5:00	-	+05
+# Aqtöbe (aka Aktobe, formerly Aktyubinsk) (KZ-15)
 Zone	Asia/Aqtobe	3:48:40	-	LMT	1924 May  2
 			4:00	-	+04	1930 Jun 21
 			5:00	-	+05	1981 Apr  1
@@ -2505,7 +2519,7 @@ Zone	Asia/Aqtobe	3:48:40	-	LMT	1924 May  2
 			4:00 RussiaAsia	+04/+05	1992 Jan 19  2:00s
 			5:00 RussiaAsia	+05/+06	2004 Oct 31  2:00s
 			5:00	-	+05
-# Mangghystaū (KZ-MAN)
+# Mangghystaū (KZ-47)
 # Aqtau was not founded until 1963, but it represents an inhabited region,
 # so include timestamps before 1963.
 Zone	Asia/Aqtau	3:21:04	-	LMT	1924 May  2
@@ -2517,7 +2531,7 @@ Zone	Asia/Aqtau	3:21:04	-	LMT	1924 May  2
 			5:00 RussiaAsia	+05/+06	1994 Sep 25  2:00s
 			4:00 RussiaAsia	+04/+05	2004 Oct 31  2:00s
 			5:00	-	+05
-# Atyraū (KZ-ATY) is like Mangghystaū except it switched from
+# Atyraū (KZ-23) is like Mangghystaū except it switched from
 # +04/+05 to +05/+06 in spring 1999, not fall 1994.
 Zone	Asia/Atyrau	3:27:44	-	LMT	1924 May  2
 			3:00	-	+03	1930 Jun 21
@@ -2528,7 +2542,7 @@ Zone	Asia/Atyrau	3:27:44	-	LMT	1924 May  2
 			5:00 RussiaAsia	+05/+06	1999 Mar 28  2:00s
 			4:00 RussiaAsia	+04/+05	2004 Oct 31  2:00s
 			5:00	-	+05
-# West Kazakhstan (KZ-ZAP)
+# West Kazakhstan (KZ-27)
 # From Paul Eggert (2016-03-18):
 # The 1989 transition is from USSR act No. 227 (1989-03-14).
 Zone	Asia/Oral	3:25:24	-	LMT	1924 May  2 # or Ural'sk
@@ -3430,19 +3444,26 @@ Zone	Asia/Karachi	4:28:12 -	LMT	1907
 # ... winter time will begin in Palestine from Saturday 10-28-2023,
 # 02:00 AM by 60 minutes back.
 #
-# From Paul Eggert (2023-03-22):
+# From Heba Hamad (2024-01-25):
+# the summer time for the years 2024,2025 will begin in Palestine
+# from Saturday at 02:00 AM by 60 minutes forward as shown below:
+# year date
+# 2024 2024-04-20
+# 2025 2025-04-12
+#
+# From Paul Eggert (2024-01-25):
 # For now, guess that spring and fall transitions will normally
 # continue to use 2022's rules, that during DST Palestine will switch
 # to standard time at 02:00 the last Saturday before Ramadan and back
-# to DST at 02:00 the first Saturday after Ramadan, and that
+# to DST at 02:00 the second Saturday after Ramadan, and that
 # if the normal spring-forward or fall-back transition occurs during
 # Ramadan the former is delayed and the latter advanced.
 # To implement this, I predicted Ramadan-oriented transition dates for
-# 2023 through 2086 by running the following program under GNU Emacs 28.2,
+# 2026 through 2086 by running the following program under GNU Emacs 29.2,
 # with the results integrated by hand into the table below.
 # Predictions after 2086 are approximated without Ramadan.
 #
-# (let ((islamic-year 1444))
+# (let ((islamic-year 1447))
 #   (require 'cal-islam)
 #   (while (< islamic-year 1510)
 #     (let ((a (calendar-islamic-to-absolute (list 9 1 islamic-year)))
@@ -3451,6 +3472,7 @@ Zone	Asia/Karachi	4:28:12 -	LMT	1907
 #       (while (/= saturday (mod (setq a (1- a)) 7)))
 #       (while (/= saturday (mod b 7))
 #         (setq b (1+ b)))
+#       (setq b (+ 7 b))
 #       (setq a (calendar-gregorian-from-absolute a))
 #       (setq b (calendar-gregorian-from-absolute b))
 #       (insert
@@ -3501,84 +3523,84 @@ Rule Palestine	2021	only	-	Oct	29	1:00	0	-
 Rule Palestine	2022	only	-	Mar	27	0:00	1:00	S
 Rule Palestine	2022	2035	-	Oct	Sat<=30	2:00	0	-
 Rule Palestine	2023	only	-	Apr	29	2:00	1:00	S
-Rule Palestine	2024	only	-	Apr	13	2:00	1:00	S
-Rule Palestine	2025	only	-	Apr	 5	2:00	1:00	S
+Rule Palestine	2024	only	-	Apr	20	2:00	1:00	S
+Rule Palestine	2025	only	-	Apr	12	2:00	1:00	S
 Rule Palestine	2026	2054	-	Mar	Sat<=30	2:00	1:00	S
 Rule Palestine	2036	only	-	Oct	18	2:00	0	-
 Rule Palestine	2037	only	-	Oct	10	2:00	0	-
 Rule Palestine	2038	only	-	Sep	25	2:00	0	-
 Rule Palestine	2039	only	-	Sep	17	2:00	0	-
-Rule Palestine	2039	only	-	Oct	22	2:00	1:00	S
-Rule Palestine	2039	2067	-	Oct	Sat<=30	2:00	0	-
 Rule Palestine	2040	only	-	Sep	 1	2:00	0	-
-Rule Palestine	2040	only	-	Oct	13	2:00	1:00	S
+Rule Palestine	2040	only	-	Oct	20	2:00	1:00	S
+Rule Palestine	2040	2067	-	Oct	Sat<=30	2:00	0	-
 Rule Palestine	2041	only	-	Aug	24	2:00	0	-
-Rule Palestine	2041	only	-	Sep	28	2:00	1:00	S
+Rule Palestine	2041	only	-	Oct	 5	2:00	1:00	S
 Rule Palestine	2042	only	-	Aug	16	2:00	0	-
-Rule Palestine	2042	only	-	Sep	20	2:00	1:00	S
+Rule Palestine	2042	only	-	Sep	27	2:00	1:00	S
 Rule Palestine	2043	only	-	Aug	 1	2:00	0	-
-Rule Palestine	2043	only	-	Sep	12	2:00	1:00	S
+Rule Palestine	2043	only	-	Sep	19	2:00	1:00	S
 Rule Palestine	2044	only	-	Jul	23	2:00	0	-
-Rule Palestine	2044	only	-	Aug	27	2:00	1:00	S
+Rule Palestine	2044	only	-	Sep	 3	2:00	1:00	S
 Rule Palestine	2045	only	-	Jul	15	2:00	0	-
-Rule Palestine	2045	only	-	Aug	19	2:00	1:00	S
+Rule Palestine	2045	only	-	Aug	26	2:00	1:00	S
 Rule Palestine	2046	only	-	Jun	30	2:00	0	-
-Rule Palestine	2046	only	-	Aug	11	2:00	1:00	S
+Rule Palestine	2046	only	-	Aug	18	2:00	1:00	S
 Rule Palestine	2047	only	-	Jun	22	2:00	0	-
-Rule Palestine	2047	only	-	Jul	27	2:00	1:00	S
+Rule Palestine	2047	only	-	Aug	 3	2:00	1:00	S
 Rule Palestine	2048	only	-	Jun	 6	2:00	0	-
-Rule Palestine	2048	only	-	Jul	18	2:00	1:00	S
+Rule Palestine	2048	only	-	Jul	25	2:00	1:00	S
 Rule Palestine	2049	only	-	May	29	2:00	0	-
-Rule Palestine	2049	only	-	Jul	 3	2:00	1:00	S
+Rule Palestine	2049	only	-	Jul	10	2:00	1:00	S
 Rule Palestine	2050	only	-	May	21	2:00	0	-
-Rule Palestine	2050	only	-	Jun	25	2:00	1:00	S
+Rule Palestine	2050	only	-	Jul	 2	2:00	1:00	S
 Rule Palestine	2051	only	-	May	 6	2:00	0	-
-Rule Palestine	2051	only	-	Jun	17	2:00	1:00	S
+Rule Palestine	2051	only	-	Jun	24	2:00	1:00	S
 Rule Palestine	2052	only	-	Apr	27	2:00	0	-
-Rule Palestine	2052	only	-	Jun	 1	2:00	1:00	S
+Rule Palestine	2052	only	-	Jun	 8	2:00	1:00	S
 Rule Palestine	2053	only	-	Apr	12	2:00	0	-
-Rule Palestine	2053	only	-	May	24	2:00	1:00	S
+Rule Palestine	2053	only	-	May	31	2:00	1:00	S
 Rule Palestine	2054	only	-	Apr	 4	2:00	0	-
-Rule Palestine	2054	only	-	May	16	2:00	1:00	S
-Rule Palestine	2055	only	-	May	 1	2:00	1:00	S
-Rule Palestine	2056	only	-	Apr	22	2:00	1:00	S
-Rule Palestine	2057	only	-	Apr	 7	2:00	1:00	S
-Rule Palestine	2058	max	-	Mar	Sat<=30	2:00	1:00	S
+Rule Palestine	2054	only	-	May	23	2:00	1:00	S
+Rule Palestine	2055	only	-	May	 8	2:00	1:00	S
+Rule Palestine	2056	only	-	Apr	29	2:00	1:00	S
+Rule Palestine	2057	only	-	Apr	14	2:00	1:00	S
+Rule Palestine	2058	only	-	Apr	 6	2:00	1:00	S
+Rule Palestine	2059	max	-	Mar	Sat<=30	2:00	1:00	S
 Rule Palestine	2068	only	-	Oct	20	2:00	0	-
 Rule Palestine	2069	only	-	Oct	12	2:00	0	-
 Rule Palestine	2070	only	-	Oct	 4	2:00	0	-
 Rule Palestine	2071	only	-	Sep	19	2:00	0	-
 Rule Palestine	2072	only	-	Sep	10	2:00	0	-
-Rule Palestine	2072	only	-	Oct	15	2:00	1:00	S
+Rule Palestine	2072	only	-	Oct	22	2:00	1:00	S
 Rule Palestine	2072	max	-	Oct	Sat<=30	2:00	0	-
 Rule Palestine	2073	only	-	Sep	 2	2:00	0	-
-Rule Palestine	2073	only	-	Oct	 7	2:00	1:00	S
+Rule Palestine	2073	only	-	Oct	14	2:00	1:00	S
 Rule Palestine	2074	only	-	Aug	18	2:00	0	-
-Rule Palestine	2074	only	-	Sep	29	2:00	1:00	S
+Rule Palestine	2074	only	-	Oct	 6	2:00	1:00	S
 Rule Palestine	2075	only	-	Aug	10	2:00	0	-
-Rule Palestine	2075	only	-	Sep	14	2:00	1:00	S
+Rule Palestine	2075	only	-	Sep	21	2:00	1:00	S
 Rule Palestine	2076	only	-	Jul	25	2:00	0	-
-Rule Palestine	2076	only	-	Sep	 5	2:00	1:00	S
+Rule Palestine	2076	only	-	Sep	12	2:00	1:00	S
 Rule Palestine	2077	only	-	Jul	17	2:00	0	-
-Rule Palestine	2077	only	-	Aug	28	2:00	1:00	S
+Rule Palestine	2077	only	-	Sep	 4	2:00	1:00	S
 Rule Palestine	2078	only	-	Jul	 9	2:00	0	-
-Rule Palestine	2078	only	-	Aug	13	2:00	1:00	S
+Rule Palestine	2078	only	-	Aug	20	2:00	1:00	S
 Rule Palestine	2079	only	-	Jun	24	2:00	0	-
-Rule Palestine	2079	only	-	Aug	 5	2:00	1:00	S
+Rule Palestine	2079	only	-	Aug	12	2:00	1:00	S
 Rule Palestine	2080	only	-	Jun	15	2:00	0	-
-Rule Palestine	2080	only	-	Jul	20	2:00	1:00	S
+Rule Palestine	2080	only	-	Jul	27	2:00	1:00	S
 Rule Palestine	2081	only	-	Jun	 7	2:00	0	-
-Rule Palestine	2081	only	-	Jul	12	2:00	1:00	S
+Rule Palestine	2081	only	-	Jul	19	2:00	1:00	S
 Rule Palestine	2082	only	-	May	23	2:00	0	-
-Rule Palestine	2082	only	-	Jul	 4	2:00	1:00	S
+Rule Palestine	2082	only	-	Jul	11	2:00	1:00	S
 Rule Palestine	2083	only	-	May	15	2:00	0	-
-Rule Palestine	2083	only	-	Jun	19	2:00	1:00	S
+Rule Palestine	2083	only	-	Jun	26	2:00	1:00	S
 Rule Palestine	2084	only	-	Apr	29	2:00	0	-
-Rule Palestine	2084	only	-	Jun	10	2:00	1:00	S
+Rule Palestine	2084	only	-	Jun	17	2:00	1:00	S
 Rule Palestine	2085	only	-	Apr	21	2:00	0	-
-Rule Palestine	2085	only	-	Jun	 2	2:00	1:00	S
+Rule Palestine	2085	only	-	Jun	 9	2:00	1:00	S
 Rule Palestine	2086	only	-	Apr	13	2:00	0	-
-Rule Palestine	2086	only	-	May	18	2:00	1:00	S
+Rule Palestine	2086	only	-	May	25	2:00	1:00	S
 
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone	Asia/Gaza	2:17:52	-	LMT	1900 Oct
@@ -3606,15 +3628,15 @@ Zone	Asia/Hebron	2:20:23	-	LMT	1900 Oct
 
 # Philippines
 
-# From Paul Eggert (2018-11-18):
+# From Paul Eggert (2024-01-21):
 # The Spanish initially used American (west-of-Greenwich) time.
 # It is unknown what time Manila kept when the British occupied it from
 # 1762-10-06 through 1764-04; for now assume it kept American time.
 # On 1844-08-16, Narciso Clavería, governor-general of the
 # Philippines, issued a proclamation announcing that 1844-12-30 was to
 # be immediately followed by 1845-01-01; see R.H. van Gent's
 # History of the International Date Line
-# https://www.staff.science.uu.nl/~gent0113/idl/idl_philippines.htm
+# https://webspace.science.uu.nl/~gent0113/idl/idl_philippines.htm
 # The rest of the data entries are from Shanks & Pottenger.
 
 # From Jesper Nørgaard Welen (2006-04-26):
@@ -4041,7 +4063,8 @@ Zone	Asia/Tashkent	4:37:11 -	LMT	1924 May  2
 # The English-language name of Vietnam's most populous city is "Ho Chi Minh
 # City"; use Ho_Chi_Minh below to avoid a name of more than 14 characters.
 
-# From Paul Eggert (2022-07-27) after a 2014 heads-up from Trần Ngọc Quân:
+# From Paul Eggert (2024-01-14) after a 2014 heads-up from Trần Ngọc Quân
+# and a 2024-01-14 heads-up from Đoàn Trần Công Danh:
 # Trần Tiến Bình's authoritative book "Lịch Việt Nam: thế kỷ XX-XXI (1901-2100)"
 # (Nhà xuất bản Văn Hoá - Thông Tin, Hanoi, 2005), pp 49-50,
 # is quoted verbatim in:
@@ -4071,24 +4094,45 @@ Zone	Asia/Tashkent	4:37:11 -	LMT	1924 May  2
 #
 # Trần cites the following sources; it's unclear which supplied the info above.
 #
-# Hoàng Xuân Hãn: "Lịch và lịch Việt Nam". Tập san Khoa học Xã hội,
-# No. 9, Paris, February 1982.
+#   Hoàng Xuân Hãn: "Lịch và lịch Việt Nam". Tập san Khoa học Xã hội,
+#   No. 9, Paris, February 1982.
+#
+#   Lê Thành Lân: "Lịch và niên biểu lịch sử hai mươi thế kỷ (0001-2010)",
+#   NXB Thống kê, Hanoi, 2000.
 #
-# Lê Thành Lân: "Lịch và niên biểu lịch sử hai mươi thế kỷ (0001-2010)",
-# NXB Thống kê, Hanoi, 2000.
+#   Lê Thành Lân: "Lịch hai thế kỷ (1802-2010) và các lịch vĩnh cửu",
+#   NXB Thuận Hoá, Huế, 1995.
 #
-# Lê Thành Lân: "Lịch hai thế kỷ (1802-2010) và các lịch vĩnh cửu",
-# NXB Thuận Hoá, Huế, 1995.
+# Here is the decision for the September 1945 transition:
+# Võ Nguyên Giáp, Việt Nam Dân Quốc Công Báo, No. 1 (1945-09-29), page 13
+# http://baochi.nlv.gov.vn/baochi/cgi-bin/baochi?a=d&d=JwvzO19450929.2.5&dliv=none
+# It says that on 1945-09-01 at 24:00, Vietnam moved back two hours, to +07.
+# It also mentions a 1945-03-29 decree (by a Japanese Goveror-General)
+# to set the time zone to +09, but does not say whether that decree
+# merely legalized an earlier change to +09.
+#
+# July 1955 transition:
+# Ngô Đình Diệm, Công Báo Việt Nam, No. 92 (1955-07-02), page 1780-1781
+# Ordinance (Dụ) No. 46 (1955-06-25)
+# http://ddsnext.crl.edu/titles/32341#?c=0&m=29&s=0&cv=4&r=0&xywh=-89%2C342%2C1724%2C1216
+# It says that on 1955-07-01 at 01:00, South Vietnam moved back 1 hour (to +07).
+#
+# December 1959 transition:
+# Ngô Đình Diệm, Công Báo Việt Nam Cộng Hòa, 1960 part 1 (1960-01-02), page 62
+# Decree (Sắc lệnh) No. 362-TTP (1959-12-30)
+# http://ddsnext.crl.edu/titles/32341#?c=0&m=138&s=0&cv=793&r=0&xywh=-54%2C1504%2C1705%2C1202
+# It says that on 1959-12-31 at 23:00, South Vietnam moved forward 1 hour (to +08).
+
 
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 		#STDOFF	7:06:30.13
 Zone Asia/Ho_Chi_Minh	7:06:30 -	LMT	1906 Jul  1
 			7:06:30	-	PLMT	1911 May  1 # Phù Liễn MT
 			7:00	-	+07	1942 Dec 31 23:00
 			8:00	-	+08	1945 Mar 14 23:00
-			9:00	-	+09	1945 Sep  2
+			9:00	-	+09	1945 Sep  1 24:00
 			7:00	-	+07	1947 Apr  1
-			8:00	-	+08	1955 Jul  1
+			8:00	-	+08	1955 Jul  1 01:00
 			7:00	-	+07	1959 Dec 31 23:00
 			8:00	-	+08	1975 Jun 13
 			7:00	-	+07

diff --git a/australasia b/australasia
@@ -420,11 +420,11 @@ Zone	Pacific/Fiji	11:55:44 -	LMT	1915 Oct 26 # Suva
 
 # French Polynesia
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone	Pacific/Gambier	 -8:59:48 -	LMT	1912 Oct # Rikitea
+Zone	Pacific/Gambier	 -8:59:48 -	LMT	1912 Oct  1 # Rikitea
 			 -9:00	-	-09
-Zone	Pacific/Marquesas -9:18:00 -	LMT	1912 Oct
+Zone	Pacific/Marquesas -9:18:00 -	LMT	1912 Oct  1
 			 -9:30	-	-0930
-Zone	Pacific/Tahiti	 -9:58:16 -	LMT	1912 Oct # Papeete
+Zone	Pacific/Tahiti	 -9:58:16 -	LMT	1912 Oct  1 # Papeete
 			-10:00	-	-10
 # Clipperton (near North America) is administered from French Polynesia;
 # it is uninhabited.
@@ -802,7 +802,7 @@ Zone Pacific/Apia	 12:33:04 -	LMT	1892 Jul  5
 # Solomon Is
 # excludes Bougainville, for which see Papua New Guinea
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone Pacific/Guadalcanal 10:39:48 -	LMT	1912 Oct # Honiara
+Zone Pacific/Guadalcanal 10:39:48 -	LMT	1912 Oct  1 # Honiara
 			11:00	-	+11
 
 # Tokelau
@@ -963,6 +963,10 @@ Zone	Pacific/Efate	11:13:16 -	LMT	1912 Jan 13 # Vila
 # Milne J. Civil time. Geogr J. 1899 Feb;13(2):173-94.
 # https://www.jstor.org/stable/1774359
 #
+# For the 1911/1912 establishment of standard time in French possessions, see:
+# Société Française de Physique, Recueil de constantes physiques (1913),
+# page 752, 18b.
+#
 # A reliable and entertaining source about time zones is
 # Derek Howse, Greenwich time and longitude, Philip Wilson Publishers (1997).
 #
@@ -2039,7 +2043,7 @@ Zone	Pacific/Efate	11:13:16 -	LMT	1912 Jan 13 # Vila
 # ordaining - by a masterpiece of diplomatic flattery - that
 # the Fourth of July should be celebrated twice in that year."
 # This happened in 1892, according to the Evening News (Sydney) of 1892-07-20.
-# https://www.staff.science.uu.nl/~gent0113/idl/idl.htm
+# https://webspace.science.uu.nl/~gent0113/idl/idl_alaska_samoa.htm
 
 # Although Shanks & Pottenger says they both switched to UT -11:30
 # in 1911, and to -11 in 1950. many earlier sources give -11

diff --git a/checknow.awk b/checknow.awk
@@ -45,7 +45,7 @@ END {
  for (zone in zone_data) {
     data = zone_data[zone]
     if (!zonenow[data]) {
-      printf "checknow.tab should have one of:%s\n", zones[data]
+      printf "zonenow.tab should have one of:%s\n", zones[data]
       zonenow[data] = zone # This suppresses duplicate diagnostics.
       status = 1
     }

diff --git a/etcetera b/etcetera
@@ -5,7 +5,7 @@
 
 # These entries are for uses not otherwise covered by the tz database.
 # Their main practical use is for platforms like Android that lack
-# support for POSIX-style TZ strings.  On such platforms these entries
+# support for POSIX.1-2017-style TZ strings.  On such platforms these entries
 # can be useful if the timezone database is wrong or if a ship or
 # aircraft at sea is not in a timezone.
 

diff --git a/europe b/europe
@@ -990,9 +990,34 @@ Zone	Europe/Sofia	1:33:16 -	LMT	1880
 # Czech Republic (Czechia)
 # Slovakia
 #
-# From Paul Eggert (2018-04-15):
-# The source for Czech data is: Kdy začíná a končí letní čas. 2018-04-15.
+# From Ivan Benovic (2024-01-30):
+# https://www.slov-lex.sk/pravne-predpisy/SK/ZZ/1946/54/
+# (This is an official link to the Czechoslovak Summer Time Act of
+# March 8, 1946 that authorizes the Czechoslovak government to set the
+# exact dates of change to summer time and back to Central European Time.
+# The act also implicitly confirms Central European Time as the
+# official time zone of Czechoslovakia and currently remains in force
+# in both the Czech Republic and Slovakia.)
+# https://www.psp.cz/eknih/1945pns/tisky/t0216_00.htm
+# (This is a link to the original legislative proposal dating back to
+# February 22, 1946. The accompanying memorandum to the proposal says
+# that an advisory committee on European railroad transportation that
+# met in Brussels in October 1945 decided that the change of time
+# should be carried out in all participating countries in a strictly
+# coordinated manner....)
+#
+# From Paul Eggert (2024-01-30):
+# The source for Czech data is: Kdy začíná a končí letní čas.
 # https://kalendar.beda.cz/kdy-zacina-a-konci-letni-cas
+# Its main text disagrees with its quoted sources only in 1918,
+# where the main text says spring and autumn transitions
+# occurred at 02:00 and 03:00 respectively (as usual),
+# whereas the 1918 source "Oznámení o zavedení letního času v roce 1918"
+# says transitions were at 01:00 and 02:00 respectively.
+# As the 1918 source appears to be a humorous piece, and it is
+# unlikely that Prague would have disagreed with its neighbors by an hour,
+# go with the main text for now.
+#
 # We know of no English-language name for historical Czech winter time;
 # abbreviate it as "GMT", as it happened to be GMT.
 #

diff --git a/leap-seconds.list b/leap-seconds.list
diff --git a/leapseconds.awk b/leapseconds.awk
@@ -1,4 +1,4 @@
-# Generate zic format 'leapseconds' from NIST format 'leap-seconds.list'.
+# Generate zic format 'leapseconds' from NIST/IERS format 'leap-seconds.list'.
 
 # This file is in the public domain.
 
@@ -21,13 +21,10 @@ BEGIN {
   print "# This file is in the public domain."
   print ""
   print "# This file is generated automatically from the data in the public-domain"
-  print "# NIST format leap-seconds.list file, which can be copied from"
-  print "# <ftp://ftp.nist.gov/pub/time/leap-seconds.list>"
-  print "# or <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>."
-  print "# The NIST file is used instead of its IERS upstream counterpart"
+  print "# NIST/IERS format leap-seconds.list file, which can be copied from"
   print "# <https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list>"
-  print "# because under US law the NIST file is public domain"
-  print "# whereas the IERS file's copyright and license status is unclear."
+  print "# or, in a variant with different comments, from"
+  print "# <ftp://ftp.boulder.nist.gov/pub/time/leap-seconds.list>."
   print "# For more about leap-seconds.list, please see"
   print "# The NTP Timescale and Leap Seconds"
   print "# <https://www.eecis.udel.edu/~mills/leap.html>."

diff --git a/localtime.c b/localtime.c
@@ -7,7 +7,7 @@
 
 /*
 ** Leap second handling from Bradley White.
-** POSIX-style TZ environment variable handling from Guy Harris.
+** POSIX.1-1988 style TZ environment variable handling from Guy Harris.
 */
 
 /*LINTLIBRARY*/
@@ -106,7 +106,7 @@ static char const UNSPEC[] = "-00";
    for ttunspecified to work without crashing.  */
 enum { CHARS_EXTRA = max(sizeof UNSPEC, 2) - 1 };
 
-/* Limit to time zone abbreviation length in POSIX-style TZ strings.
+/* Limit to time zone abbreviation length in POSIX.1-2017-style TZ strings.
    This is distinct from TZ_MAX_CHARS, which limits TZif file contents.  */
 #ifndef TZNAME_MAXIMUM
 # define TZNAME_MAXIMUM 255
@@ -935,7 +935,8 @@ getoffset(register const char *strp, int_fast32_t *const offsetp)
 
 /*
 ** Given a pointer into a timezone string, extract a rule in the form
-** date[/time]. See POSIX section 8 for the format of "date" and "time".
+** date[/time]. See POSIX Base Definitions section 8.3 variable TZ
+** for the format of "date" and "time".
 ** If a valid rule is not found, return NULL.
 ** Otherwise, return a pointer to the first character not part of the rule.
 */
@@ -1079,7 +1080,7 @@ transtime(const int year, register const struct rule *const rulep,
 }
 
 /*
-** Given a POSIX section 8-style TZ string, fill in the rule tables as
+** Given a POSIX.1-2017-style TZ string, fill in the rule tables as
 ** appropriate.
 */
 
@@ -1204,7 +1205,7 @@ tzparse(const char *name, struct state *sp, struct state const *basep)
 			}
 
 			yearlim = yearbeg;
-			if (increment_overflow(&yearlim, YEARSPERREPEAT + 1))
+			if (increment_overflow(&yearlim, years_of_observations))
 			  yearlim = INT_MAX;
 			for (year = yearbeg; year < yearlim; year++) {
 				int_fast32_t
@@ -1241,7 +1242,7 @@ tzparse(const char *name, struct state *sp, struct state const *basep)
 				if (endtime < leaplo) {
 				  yearlim = year;
 				  if (increment_overflow(&yearlim,
-							 YEARSPERREPEAT + 1))
+							 years_of_observations))
 				    yearlim = INT_MAX;
 				}
 				if (increment_overflow_time
@@ -1253,7 +1254,7 @@ tzparse(const char *name, struct state *sp, struct state const *basep)
 			if (! timecnt) {
 				sp->ttis[0] = sp->ttis[1];
 				sp->typecnt = 1;	/* Perpetual DST.  */
-			} else if (YEARSPERREPEAT < year - yearbeg)
+			} else if (years_of_observations <= year - yearbeg)
 				sp->goback = sp->goahead = true;
 		} else {
 			register int_fast32_t	theirstdoffset;
@@ -1312,8 +1313,8 @@ tzparse(const char *name, struct state *sp, struct state const *basep)
 					/*
 					** Transitions from DST to DDST
 					** will effectively disappear since
-					** POSIX provides for only one DST
-					** offset.
+					** POSIX.1-2017 provides for only one
+					** DST offset.
 					*/
 					if (isdst && !sp->ttis[j].tt_ttisstd) {
 						sp->ats[i] += dstoffset -
@@ -1483,7 +1484,8 @@ tzfree(timezone_t sp)
 **
 ** If successful and SETNAME is nonzero,
 ** set the applicable parts of tzname, timezone and altzone;
-** however, it's OK to omit this step if the timezone is POSIX-compatible,
+** however, it's OK to omit this step
+** if the timezone is compatible with POSIX.1-2017
 ** since in that case tzset should have already done this step correctly.
 ** SETNAME's type is int_fast32_t for compatibility with gmtsub,
 ** but it is actually a boolean and its value should be 0 or 1.
@@ -2292,15 +2294,18 @@ timelocal(struct tm *tmp)
 		tmp->tm_isdst = -1;	/* in case it wasn't initialized */
 	return mktime(tmp);
 }
-#else
+#endif
+
+#ifndef EXTERN_TIMEOFF
 # ifndef timeoff
 #  define timeoff my_timeoff /* Don't collide with OpenBSD 7.4 <time.h>.  */
 # endif
-static
+# define EXTERN_TIMEOFF static
 #endif
+
 /* This function is obsolescent and may disapper in future releases.
    Callers can instead use mktime_z with a fixed-offset zone.  */
-time_t
+EXTERN_TIMEOFF time_t
 timeoff(struct tm *tmp, long offset)
 {
   if (tmp)

diff --git a/newstrftime.3 b/newstrftime.3
@@ -64,7 +64,7 @@ strftime \- format date and time
 The
 .B strftime
 function formats the information from
-.I timeptr
+.BI * timeptr
 into the array pointed to by
 .I buf
 according to the string pointed to by
@@ -85,47 +85,94 @@ bytes are placed into the array.
 .PP
 Each conversion specification is replaced by the characters as
 follows which are then copied into the array.
+The characters depend on the values of zero or more members of
+.BI * timeptr
+as specified by brackets in the description.
+If a bracketed member name is followed by
+.q + ,
+.B strftime
+can use the named member even though POSIX.1-2017 does not list it;
+if the name is followed by
+.q \*- ,
+.B strftime
+ignores the member even though POSIX.1-2017 lists it
+which means portable code should set it.
+For portability,
+.BI * timeptr
+should be initialized as if by a successful call to
+.BR gmtime ,
+.BR localtime ,
+.BR mktime ,
+.BR timegm ,
+or similar functions.
 .TP
 %A
 is replaced by the locale's full weekday name.
+.RI [ tm_wday ]
 .TP
 %a
 is replaced by the locale's abbreviated weekday name.
+.RI [ tm_wday ]
 .TP
 %B
 is replaced by the locale's full month name.
+.RI [ tm_mon ]
 .TP
 %b or %h
 is replaced by the locale's abbreviated month name.
+.RI [ tm_mon ]
 .TP
 %C
 is replaced by the century (a year divided by 100 and truncated to an integer)
-as a decimal number [00,99].
+as a decimal number, with at least two digits by default.
+.RI [ tm_year ]
 .TP
 %c
 is replaced by the locale's appropriate date and time representation.
+.RI [ tm_year ,
+.IR tm_yday ,
+.IR tm_mon ,
+.IR tm_mday ,
+.IR tm_wday ,
+.IR tm_hour ,
+.IR tm_min ,
+.IR tm_sec ,
+.IR tm_gmtoff +,
+.IR tm_zone +,
+.IR tm_isdst \*-].
 .TP
 %D
 is equivalent to
 .c %m/%d/%y .
+.RI [ tm_year ,
+.IR tm_mon ,
+.IR tm_mday ]
 .TP
 %d
 is replaced by the day of the month as a decimal number [01,31].
+.RI [ tm_mday ]
 .TP
 %e
 is replaced by the day of month as a decimal number [1,31];
 single digits are preceded by a blank.
+.RI [ tm_mday ]
 .TP
 %F
 is equivalent to
 .c %Y-%m-%d
 (the ISO 8601 date format).
+.RI [ tm_year ,
+.IR tm_mon ,
+.IR tm_mday ]
 .TP
 %G
 is replaced by the ISO 8601 year with century as a decimal number.
 See also the
 .c %V
 conversion specification.
+.RI [ tm_year ,
+.IR tm_yday ,
+.IR tm_wday ]
 .TP
 %g
 is replaced by the ISO 8601 year without century as a decimal number [00,99].
@@ -134,29 +181,39 @@ This is the year that includes the greater part of the week.
 See also the
 .c %V
 conversion specification.
+.RI [ tm_year ,
+.IR tm_yday ,
+.IR tm_wday ]
 .TP
 %H
 is replaced by the hour (24-hour clock) as a decimal number [00,23].
+.RI [ tm_hour ]
 .TP
 %I
 is replaced by the hour (12-hour clock) as a decimal number [01,12].
+.RI [ tm_hour ]
 .TP
 %j
 is replaced by the day of the year as a decimal number [001,366].
+.RI [ tm_yday ]
 .TP
 %k
 is replaced by the hour (24-hour clock) as a decimal number [0,23];
 single digits are preceded by a blank.
+.RI [ tm_hour ]
 .TP
 %l
 is replaced by the hour (12-hour clock) as a decimal number [1,12];
 single digits are preceded by a blank.
+.RI [ tm_hour ]
 .TP
 %M
 is replaced by the minute as a decimal number [00,59].
+.RI [ tm_min ]
 .TP
 %m
 is replaced by the month as a decimal number [01,12].
+.RI [ tm_mon ]
 .TP
 %n
 is replaced by a newline.
@@ -166,39 +223,73 @@ is replaced by the locale's equivalent of either
 .q AM
 or
 .q PM .
+.RI [ tm_hour ]
 .TP
 %R
 is replaced by the time in the format
 .c %H:%M .
+.RI [ tm_hour ,
+.IR tm_min ]
 .TP
 %r
 is replaced by the locale's representation of 12-hour clock time
 using AM/PM notation.
+.RI [ tm_hour ,
+.IR tm_min ,
+.IR tm_sec ]
 .TP
 %S
 is replaced by the second as a decimal number [00,60].
 The range of
 seconds is [00,60] instead of [00,59] to allow for the periodic occurrence
 of leap seconds.
+.RI [ tm_sec ]
 .TP
 %s
 is replaced by the number of seconds since the Epoch (see
 .BR ctime (3)).
+Although %s is reliable in this implementation,
+it can have glitches on other platforms (notably platforms lacking
+.IR tm_gmtoff ),
+so portable code should format a
+.B time_t
+value directly via something like
+.B sprintf
+instead of via
+.B localtime
+followed by
+.B strftime
+with "%s".
+.RI [ tm_year ,
+.IR tm_mon ,
+.IR tm_mday ,
+.IR tm_hour ,
+.IR tm_min ,
+.IR tm_sec ,
+.IR tm_gmtoff +,
+.IR tm_isdst \*-].
 .TP
 %T
 is replaced by the time in the format
 .c %H:%M:%S .
+.RI [ tm_hour ,
+.IR tm_min ,
+.IR tm_sec ]
 .TP
 %t
 is replaced by a tab.
 .TP
 %U
 is replaced by the week number of the year (Sunday as the first day of
 the week) as a decimal number [00,53].
+.RI [ tm_wday ,
+.IR tm_yday ,
+.IR tm_year \*-]
 .TP
 %u
 is replaced by the weekday (Monday as the first day of the week)
 as a decimal number [1,7].
+.RI [ tm_wday ]
 .TP
 %V
 is replaced by the week number of the year (Monday as the first day of
@@ -208,30 +299,64 @@ it is week 53 of the previous year, and the next week is week 1.
 The year is given by the
 .c %G
 conversion specification.
+.RI [ tm_year ,
+.IR tm_yday ,
+.IR tm_wday ]
 .TP
 %W
 is replaced by the week number of the year (Monday as the first day of
 the week) as a decimal number [00,53].
+.RI [ tm_yday ,
+.IR tm_wday ]
 .TP
 %w
 is replaced by the weekday (Sunday as the first day of the week)
 as a decimal number [0,6].
+.RI [ tm_year ,
+.IR tm_yday ,
+.IR tm_wday ]
 .TP
 %X
 is replaced by the locale's appropriate time representation.
+.RI [ tm_year \*-,
+.IR tm_yday \*-,
+.IR tm_mon \*-,
+.IR tm_mday \*-,
+.IR tm_wday \*-,
+.IR tm_hour ,
+.IR tm_min ,
+.IR tm_sec ,
+.IR tm_gmtoff +,
+.IR tm_zone +,
+.IR tm_isdst \*-].
 .TP
 %x
 is replaced by the locale's appropriate date representation.
+.RI [ tm_year ,
+.IR tm_yday ,
+.IR tm_mon ,
+.IR tm_mday ,
+.IR tm_wday ,
+.IR tm_hour \*-,
+.IR tm_min \*-,
+.IR tm_sec \*-,
+.IR tm_gmtoff \*-,
+.IR tm_zone \*-,
+.IR tm_isdst \*-].
 .TP
 %Y
 is replaced by the year with century as a decimal number.
+.RI [ tm_year ]
 .TP
 %y
 is replaced by the year without century as a decimal number [00,99].
+.RI [ tm_year ]
 .TP
 %Z
 is replaced by the time zone abbreviation,
 or by the empty string if this is not determinable.
+.RI [ tm_zone +,
+.IR tm_isdst \*-]
 .TP
 %z
 is replaced by the offset from the Prime Meridian
@@ -244,6 +369,9 @@ but local time is indeterminate; by convention this is used for
 locations while uninhabited, and corresponds to a zero offset when the
 time zone abbreviation begins with
 .q "\*-" .
+.RI [ tm_gmtoff +,
+.IR tm_zone +,
+.IR tm_isdst \*-]
 .TP
 %%
 is replaced by a single %.
@@ -252,6 +380,26 @@ is replaced by a single %.
 is replaced by the locale's date and time in
 .BR date (1)
 format.
+.RI [ tm_year ,
+.IR tm_yday ,
+.IR tm_mon ,
+.IR tm_mday ,
+.IR tm_wday ,
+.IR tm_hour ,
+.IR tm_min ,
+.IR tm_sec ,
+.IR tm_gmtoff ,
+.IR tm_zone ]
+.PP
+As a side effect,
+.B strftime
+also behaves as if
+.B tzset
+were called.
+This is for compatibility with older platforms, as required by POSIX;
+it is not needed for
+.BR tzset 's
+own use.
 .SH "RETURN VALUE"
 If the conversion is successful,
 .B strftime

diff --git a/newtzset.3 b/newtzset.3
@@ -9,9 +9,9 @@ tzset \- initialize time conversion information
 .el .ds - \-
 .B #include <time.h>
 .PP
-.B timezone_t tzalloc(char const *TZ);
+.BI "timezone_t tzalloc(char const *" TZ );
 .PP
-.B void tzfree(timezone_t tz);
+.BI "void tzfree(timezone_t " tz );
 .PP
 .B void tzset(void);
 .PP
@@ -31,62 +31,30 @@ The
 .B tzalloc
 function
 allocates and returns a timezone object described by
-.BR TZ .
-If
-.B TZ
-is not a valid timezone description, or if the object cannot be allocated,
-.B tzalloc
-returns a null pointer and sets
-.BR errno .
-.PP
-The
-.B tzfree
-function
-frees a timezone object
-.BR tz ,
-which should have been successfully allocated by
-.BR tzalloc .
-This invalidates any
-.B tm_zone
-pointers that
-.B tz
-was used to set.
-.PP
-The
-.B tzset
-function
-acts like
-.BR tzalloc(getenv("TZ")) ,
-except it saves any resulting timezone object into internal
-storage that is accessed by
-.BR localtime ,
-.BR localtime_r ,
-and
-.BR mktime .
-The anonymous shared timezone object is freed by the next call to
-.BR tzset .
-If the implied call to
-.B tzalloc
-fails,
-.B tzset
-falls back on Universal Time (UT).
+.IR TZ .
 .PP
 If
-.B TZ
-is null, the best available approximation to local (wall
+.I TZ
+is a null pointer,
+.B tzalloc
+uses the best available approximation to local (wall
 clock) time, as specified by the
 .BR tzfile (5)-format
 file
 .B localtime
-in the system time conversion information directory, is used.
+in the system time conversion information directory.
+.PP
 If
-.B TZ
+.I TZ
 is the empty string,
-UT is used, with the abbreviation "UTC"
+.B tzalloc
+uses Universal Time (UT), with the abbreviation "UTC"
 and without leap second correction; please see
 .BR newctime (3)
-for more about UT, UTC, and leap seconds.  If
-.B TZ
+for more about UT, UTC, and leap seconds.
+.PP
+If
+.I TZ
 is nonnull and nonempty:
 .IP
 if the value begins with a colon, it is used as a pathname of a file
@@ -98,18 +66,19 @@ and, if that file cannot be read, is used directly as a specification of
 the time conversion information.
 .PP
 When
-.B TZ
-is used as a pathname, if it begins with a slash,
-it is used as an absolute pathname; otherwise,
-it is used as a pathname relative to a system time conversion information
+.I TZ
+contents are used as a pathname, a pathname beginning with
+.q "/"
+is used as-is; otherwise
+the pathname is relative to a system time conversion information
 directory.
 The file must be in the format specified in
 .BR tzfile (5).
 .PP
 When
-.B TZ
+.I TZ
 is used directly as a specification of the time conversion information,
-it must have the following syntax (spaces inserted for clarity):
+it must have the following syntax:
 .IP
 \fIstd\|offset\fR[\fIdst\fR[\fIoffset\fR][\fB,\fIrule\fR]]
 .PP
@@ -196,7 +165,7 @@ describes when the change back happens.  Each
 .I time
 field describes when, in current local time, the change to the other
 time is made.
-As an extension to POSIX, daylight saving is assumed to be in effect
+As an extension to POSIX.1-2017, daylight saving is assumed to be in effect
 all year if it begins January 1 at 00:00 and ends December 31 at
 24:00 plus the difference between daylight saving and standard time,
 leaving no room for standard time in the calendar.
@@ -243,11 +212,11 @@ The
 .I time
 has the same format as
 .I offset
-except that POSIX does not allow a leading sign (\c
+except that POSIX.1-2017 does not allow a leading sign (\c
 .q "\*-"
 or
 .q "+" ).
-As an extension to POSIX, the hours part of
+As an extension to POSIX.1-2017, the hours part of
 .I time
 can range from \-167 through 167; this allows for unusual rules such
 as
@@ -259,9 +228,9 @@ is not given, is
 .RE
 .LP
 Here are some examples of
-.B TZ
+.I TZ
 values that directly specify the timezone; they use some of the
-extensions to POSIX.
+extensions to POSIX.1-2017.
 .TP
 .B EST5
 stands for US Eastern Standard
@@ -307,7 +276,7 @@ and
 .q "\*-02".
 .PP
 If
-.B TZ
+.I TZ
 specifies daylight saving time but does not specify a
 .IR rule ,
 and the optional
@@ -323,20 +292,85 @@ standard and daylight saving time offsets from UT
 replaced by those specified by the
 .I offset
 values in
-.BR TZ .
+.IR TZ .
 However, the
 .B posixrules
 file is obsolete: if it is present it is only for backward compatibility,
 and it does not work reliably.
-Therefore, applications that specify a
-.B TZ
-string with daylight saving time should specify rules explicitly.
+Therefore, if a
+.I TZ
+string directly specifies a timezone with daylight saving time,
+it should specify the daylight saving rules explicitly.
 .PP
 For compatibility with System V Release 3.1, a semicolon
 .RB ( ; )
 may be used to separate the
 .I rule
-from the rest of the specification.
+from the rest of the specification;
+this is an extension to POSIX.
+.PP
+The
+.B tzfree
+function
+frees a timezone object
+.IR tz ,
+which should have been successfully allocated by
+.BR tzalloc .
+This invalidates any
+.B tm_zone
+pointers that
+.I tz
+was used to set.
+.PP
+The
+.B tzset
+function
+acts like
+.BR tzalloc(getenv("TZ")) ,
+except it saves any resulting timezone object into internal
+storage that is accessed by
+.BR localtime ,
+.BR localtime_r ,
+and
+.BR mktime .
+The anonymous shared timezone object is freed by the next call to
+.BR tzset .
+If the implied call to
+.B getenv
+fails,
+.B tzset
+acts like
+.BR tzalloc(nullptr) ;
+if the implied call to
+.B tzalloc
+fails,
+.B tzset
+falls back on UT.
+.SH "RETURN VALUE"
+If successful, the
+.B tzalloc
+function returns a nonnull pointer to the newly allocated object.
+Otherwise, it returns a null pointer and sets
+.IR errno .
+.SH ERRORS
+.TP
+.B EOVERFLOW
+.I TZ
+directly specifies time conversion information,
+and contains an integer out of machine range
+or a time zone abbreviation that is too long for this platform.
+.PP
+The
+.B tzalloc
+function may also fail and set
+.I errno
+for any of the errors specified for the routines
+.BR access (2),
+.BR close (2),
+.BR malloc (3),
+.BR open (2),
+and
+.BR read (2).
 .SH FILES
 .ta \w'/usr/share/zoneinfo/posixrules\0\0'u
 /etc/localtime	local timezone file

diff --git a/northamerica b/northamerica
@@ -1268,6 +1268,10 @@ Zone America/Menominee	-5:50:27 -	LMT	1885 Sep 18 12:00
 #	<http://cs.ucla.edu/~eggert/The-Waste-of-Daylight-19th.pdf>
 #	[PDF] (1914-03)
 #
+# For the 1911/1912 establishment of standard time in French possessions, see:
+# Société Française de Physique, Recueil de constantes physiques (1913),
+# page 752, 18b.
+#
 # See the 'europe' file for Greenland.
 
 # Canada
@@ -1354,7 +1358,7 @@ Zone America/Menominee	-5:50:27 -	LMT	1885 Sep 18 12:00
 # From Paul Eggert (2014-10-18):
 # H. David Matthews and Mary Vincent's map
 # "It's about TIME", _Canadian Geographic_ (September-October 1998)
-# http://www.canadiangeographic.ca/Magazine/SO98/alacarte.asp
+# https://web.archive.org/web/19990827055050/https://canadiangeographic.ca/SO98/geomap.htm
 # contains detailed boundaries for regions observing nonstandard
 # time and daylight saving time arrangements in Canada circa 1998.
 #
@@ -1642,6 +1646,15 @@ Zone America/Moncton	-4:19:08 -	LMT	1883 Dec  9
 #     Some cities in the United States have pushed the deadline back
 #     three weeks and will change over from daylight saving in October.
 
+# From Chris Walton (2024-01-09):
+# The [Toronto] changes in 1947, 1948, and 1949 took place at 2:00 a.m. local
+# time instead of midnight....  Toronto Daily Star - ...
+# April 2, 1947 - Page 39 ... April 7, 1948 - Page 13 ...
+# April 2, 1949 - Page 1 ... April 7, 1949 - Page 24 ...
+# November 25, 1949 - Page 52 ... April 21, 1950 - Page 14 ...
+# September 19, 1950 - Page 46 ... September 20, 1950 - Page 3 ...
+# November 24, 1950 - Page 21
+
 # From Arthur David Olson (2010-07-17):
 #
 # "Standard Time and Time Zones in Canada" appeared in
@@ -1703,13 +1716,9 @@ Rule	Toronto	1927	1937	-	Sep	Sun>=25	2:00	0	S
 Rule	Toronto	1928	1937	-	Apr	Sun>=25	2:00	1:00	D
 Rule	Toronto	1938	1940	-	Apr	lastSun	2:00	1:00	D
 Rule	Toronto	1938	1939	-	Sep	lastSun	2:00	0	S
-Rule	Toronto	1945	1946	-	Sep	lastSun	2:00	0	S
-Rule	Toronto	1946	only	-	Apr	lastSun	2:00	1:00	D
-Rule	Toronto	1947	1949	-	Apr	lastSun	0:00	1:00	D
-Rule	Toronto	1947	1948	-	Sep	lastSun	0:00	0	S
-Rule	Toronto	1949	only	-	Nov	lastSun	0:00	0	S
-Rule	Toronto	1950	1973	-	Apr	lastSun	2:00	1:00	D
-Rule	Toronto	1950	only	-	Nov	lastSun	2:00	0	S
+Rule	Toronto	1945	1948	-	Sep	lastSun	2:00	0	S
+Rule	Toronto	1946	1973	-	Apr	lastSun	2:00	1:00	D
+Rule	Toronto	1949	1950	-	Nov	lastSun	2:00	0	S
 Rule	Toronto	1951	1956	-	Sep	lastSun	2:00	0	S
 # Shanks & Pottenger say Toronto ended DST a week early in 1971,
 # namely on 1971-10-24, but Mark Brader wrote (2003-05-31) that this
@@ -3432,7 +3441,7 @@ Zone	America/Jamaica	-5:07:10 -	LMT	1890        # Kingston
 # Martinique
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
 Zone America/Martinique	-4:04:20 -      LMT	1890        # Fort-de-France
-			-4:04:20 -	FFMT	1911 May    # Fort-de-France MT
+			-4:04:20 -	FFMT	1911 May  1 # Fort-de-France MT
 			-4:00	-	AST	1980 Apr  6
 			-4:00	1:00	ADT	1980 Sep 28
 			-4:00	-	AST
@@ -3539,7 +3548,7 @@ Zone America/Puerto_Rico -4:24:25 -	LMT	1899 Mar 28 12:00 # San Juan
 # St Pierre and Miquelon
 # There are too many St Pierres elsewhere, so we'll use 'Miquelon'.
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone America/Miquelon	-3:44:40 -	LMT	1911 May 15 # St Pierre
+Zone America/Miquelon	-3:44:40 -	LMT	1911 Jun 15 # St Pierre
 			-4:00	-	AST	1980 May
 			-3:00	-	-03	1987
 			-3:00	Canada	-03/-02

diff --git a/private.h b/private.h
@@ -756,7 +756,7 @@ struct tm *offtime(time_t const *, long);
 time_t timelocal(struct tm *);
 # endif
 # if TZ_TIME_T || !defined timeoff
-time_t timeoff(struct tm *, long);
+#  define EXTERN_TIMEOFF
 # endif
 # if TZ_TIME_T || !defined time2posix
 time_t time2posix(time_t);
@@ -768,7 +768,8 @@ time_t posix2time(time_t);
 
 /* Infer TM_ZONE on systems where this information is known, but suppress
    guessing if NO_TM_ZONE is defined.  Similarly for TM_GMTOFF.  */
-#if (defined __GLIBC__ \
+#if (200809 < _POSIX_VERSION \
+     || defined __GLIBC__ \
      || defined __tm_zone /* musl */ \
      || defined __FreeBSD__ || defined __NetBSD__ || defined __OpenBSD__ \
      || (defined __APPLE__ && defined __MACH__))
@@ -898,6 +899,19 @@ static_assert(! TYPE_SIGNED(time_t) || ! SIGNED_PADDING_CHECK_NEEDED
 # define UNINIT_TRAP 0
 #endif
 
+/* localtime.c sometimes needs access to timeoff if it is not already public.
+   tz_private_timeoff should be used only by localtime.c.  */
+#if (!defined EXTERN_TIMEOFF \
+     && defined TM_GMTOFF && (200809 < _POSIX_VERSION || ! UNINIT_TRAP))
+# ifndef timeoff
+#  define timeoff tz_private_timeoff
+# endif
+# define EXTERN_TIMEOFF
+#endif
+#ifdef EXTERN_TIMEOFF
+time_t timeoff(struct tm *, long);
+#endif
+
 #ifdef DEBUG
 # undef unreachable
 # define unreachable() abort()
@@ -957,6 +971,18 @@ enum {
 #define SECSPERREPEAT		((int_fast64_t) DAYSPERREPEAT * SECSPERDAY)
 #define AVGSECSPERYEAR		(SECSPERREPEAT / YEARSPERREPEAT)
 
+/* How many years to generate (in zic.c) or search through (in localtime.c).
+   This is two years larger than the obvious 400, to avoid edge cases.
+   E.g., suppose a non-POSIX.1-2017 rule applies from 2012 on with transitions
+   in March and September, plus one-off transitions in November 2013.
+   If zic looked only at the last 400 years, it would set max_year=2413,
+   with the intent that the 400 years 2014 through 2413 will be repeated.
+   The last transition listed in the tzfile would be in 2413-09,
+   less than 400 years after the last one-off transition in 2013-11.
+   Two years is not overkill for localtime.c, as a one-year bump
+   would mishandle 2023d's America/Ciudad_Juarez for November 2422.  */
+enum { years_of_observations = YEARSPERREPEAT + 2 };
+
 enum {
   TM_SUNDAY,
   TM_MONDAY,

diff --git a/southamerica b/southamerica
@@ -1570,8 +1570,11 @@ Zone Atlantic/Stanley	-3:51:24 -	LMT	1890
 			-3:00	-	-03
 
 # French Guiana
+# For the 1911/1912 establishment of standard time in French possessions, see:
+# Société Française de Physique, Recueil de constantes physiques (1913),
+# page 752, 18b.
 # Zone	NAME		STDOFF	RULES	FORMAT	[UNTIL]
-Zone America/Cayenne	-3:29:20 -	LMT	1911 Jul
+Zone America/Cayenne	-3:29:20 -	LMT	1911 Jul  1
 			-4:00	-	-04	1967 Oct
 			-3:00	-	-03
 

diff --git a/strftime.c b/strftime.c
@@ -327,11 +327,12 @@ _fmt(const char *format, const struct tm *t, char *pt,
 					tm.tm_mday = t->tm_mday;
 					tm.tm_mon = t->tm_mon;
 					tm.tm_year = t->tm_year;
+#ifdef TM_GMTOFF
+					mkt = timeoff(&tm, t->TM_GMTOFF);
+#else
 					tm.tm_isdst = t->tm_isdst;
-#if defined TM_GMTOFF && ! UNINIT_TRAP
-					tm.TM_GMTOFF = t->TM_GMTOFF;
-#endif
 					mkt = mktime(&tm);
+#endif
 					/* If mktime fails, %s expands to the
 					   value of (time_t) -1 as a failure
 					   marker; this is better in practice

diff --git a/theory.html b/theory.html
@@ -95,7 +95,7 @@ <h2 id="scope">Scope of the <code><abbr>tz</abbr></code> database</h2>
 Edition.
 Because the database's scope encompasses real-world changes to civil
 timekeeping, its model for describing time is more complex than the
-standard and daylight saving times supported by POSIX.
+standard and daylight saving times supported by POSIX.1-2017.
 A <code><abbr>tz</abbr></code> timezone corresponds to a ruleset that can
 have more than two changes per year, these changes need not merely
 flip back and forth between two alternatives, and the rules themselves
@@ -187,7 +187,7 @@ <h2 id="naming">Timezone identifiers</h2>
     href="https://en.wikipedia.org/wiki/ASCII">ASCII</a> letters,
     '<code>.</code>', '<code>-</code>' and '<code>_</code>'.
     Do not use digits, as that might create an ambiguity with <a
-    href="https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">POSIX
+    href="https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03">POSIX.1-2017
     <code>TZ</code> strings</a>.
     A file name component must not exceed 14 characters or start with
     '<code>-</code>'.
@@ -362,6 +362,11 @@ <h2 id="naming">Timezone identifiers</h2>
 but conforms to the older-version guidelines related to <abbr>ISO</abbr> 3166-1;
 it lists only one country code per entry and unlike <code>zone1970.tab</code>
 it can list names defined in <code>backward</code>.
+Applications that process only timestamps from now on can instead use the file
+<code>zonenow.tab</code>, which partitions the world more coarsely,
+into regions where clocks agree now and in the predicted future;
+this file is smaller and simpler than <code>zone1970.tab</code>
+and <code>zone.tab</code>.
 </p>
 
 <p>
@@ -373,7 +378,7 @@ <h2 id="naming">Timezone identifiers</h2>
 and no great weight should be attached to whether a link
 is defined in <code>backward</code> or in some other file.
 The source file <code>etcetera</code> defines names that may be useful
-on platforms that do not support POSIX-style <code>TZ</code> strings;
+on platforms that do not support POSIX.1-2017-style <code>TZ</code> strings;
 no other source file other than <code>backward</code>
 contains links to its zones.
 One of <code>etcetera</code>'s names is <code>Etc/UTC</code>,
@@ -421,7 +426,7 @@ <h2 id="abbreviations">Time zone abbreviations</h2>
     expression <code>[-+[:alnum:]]{3,6}</code> should match the
     abbreviation.
     This guarantees that all abbreviations could have been specified by a
-    POSIX <code>TZ</code> string.
+    POSIX.1-2017 <code>TZ</code> string.
     </p>
   </li>
   <li>
@@ -765,12 +770,12 @@ <h2 id="accuracy">Accuracy of the <code><abbr>tz</abbr></code> database</h2>
     calendar with 24-hour days. These divergences range from
     relatively minor, such as Japanese bars giving times like "24:30" for the
     wee hours of the morning, to more-significant differences such as <a
-    href="https://www.pri.org/stories/2015-01-30/if-you-have-meeting-ethiopia-you-better-double-check-time">the
+    href="https://theworld.org/stories/2015-01-30/if-you-have-meeting-ethiopia-you-better-double-check-time">the
     east African practice of starting the day at dawn</a>, renumbering
     the Western 06:00 to be 12:00. These practices are largely outside
     the scope of the <code><abbr>tz</abbr></code> code and data, which
     provide only limited support for date and time localization
-    such as that required by POSIX.
+    such as that required by POSIX.1-2017.
     If <abbr>DST</abbr> is not used a different time zone
     can often do the trick; for example, in Kenya a <code>TZ</code> setting
     like <code>&lt;-03&gt;3</code> or <code>America/Cayenne</code> starts
@@ -867,23 +872,23 @@ <h2 id="functions">Time and date functions</h2>
 an older <code>zic</code>.
 </p>
 
-<h3 id="POSIX">POSIX properties and limitations</h3>
+<h3 id="POSIX">POSIX.1-2017 properties and limitations</h3>
 <ul>
   <li>
     <p>
-    In POSIX, time display in a process is controlled by the
+    In POSIX.1-2017, time display in a process is controlled by the
     environment variable <code>TZ</code>.
-    Unfortunately, the POSIX
+    Unfortunately, the POSIX.1-2017
     <code>TZ</code> string takes a form that is hard to describe and
     is error-prone in practice.
-    Also, POSIX <code>TZ</code> strings cannot deal with daylight
+    Also, POSIX.1-2017 <code>TZ</code> strings cannot deal with daylight
     saving time rules not based on the Gregorian calendar (as in
     Morocco), or with situations where more than two time zone
     abbreviations or <abbr>UT</abbr> offsets are used in an area.
     </p>
 
     <p>
-    The POSIX <code>TZ</code> string takes the following form:
+    The POSIX.1-2017 <code>TZ</code> string takes the following form:
     </p>
 
     <p>
@@ -950,7 +955,7 @@ <h3 id="POSIX">POSIX properties and limitations</h3>
     </dl>
 
     <p>
-    Here is an example POSIX <code>TZ</code> string for New
+    Here is an example POSIX.1-2017 <code>TZ</code> string for New
     Zealand after 2007.
     It says that standard time (<abbr>NZST</abbr>) is 12 hours ahead
     of <abbr>UT</abbr>, and that daylight saving time
@@ -961,7 +966,7 @@ <h3 id="POSIX">POSIX properties and limitations</h3>
     <pre><code>TZ='NZST-12NZDT,M9.5.0,M4.1.0/3'</code></pre>
 
     <p>
-    This POSIX <code>TZ</code> string is hard to remember, and
+    This POSIX.1-2017 <code>TZ</code> string is hard to remember, and
     mishandles some timestamps before 2008.
     With this package you can use this instead:
     </p>
@@ -999,7 +1004,7 @@ <h3 id="POSIX">POSIX properties and limitations</h3>
     limit phone calls to off-peak hours.
   </li>
   <li>
-    POSIX provides no convenient and efficient way to determine
+    POSIX.1-2017 provides no convenient and efficient way to determine
     the <abbr>UT</abbr> offset and time zone abbreviation of arbitrary
     timestamps, particularly for timezones
     that do not fit into the POSIX model.
@@ -1026,14 +1031,14 @@ <h3 id="POSIX">POSIX properties and limitations</h3>
   </li>
 </ul>
 
-<h3 id="POSIX-extensions">Extensions to POSIX in the
+<h3 id="POSIX-extensions">Extensions to POSIX.1-2017 in the
 <code><abbr>tz</abbr></code> code</h3>
 <ul>
   <li>
     <p>
     The <code>TZ</code> environment variable is used in generating
     the name of a file from which time-related information is read
-    (or is interpreted à la POSIX); <code>TZ</code> is no longer
+    (or is interpreted à la POSIX.1-2017); <code>TZ</code> is no longer
     constrained to be a string containing abbreviations
     and numeric data as described <a href="#POSIX">above</a>.
     The file's format is <dfn><abbr>TZif</abbr></dfn>,

diff --git a/tz-art.html b/tz-art.html
diff --git a/tz-link.html b/tz-link.html
@@ -114,7 +114,7 @@ <h2 id="tzdb">The <code><abbr title="time zone">tz</abbr></code> database</h2>
 and switched back in 2006.
 To use the database on an extended <a
 href="https://en.wikipedia.org/wiki/POSIX"><abbr
-title="Portable Operating System Interface">POSIX</abbr></a>
+title="Portable Operating System Interface">POSIX</abbr>.1-2017</a>
 implementation set the <code><abbr>TZ</abbr></code>
 environment variable to the location's full name,
 e.g., <code><abbr>TZ</abbr>="America/New_York"</code>.</p>
@@ -172,7 +172,7 @@ <h2 id="download">Downloading the <code><abbr>tz</abbr></code> database</h2>
 ustar interchange format</a>, compressed as described above;
 older releases use a nearly compatible format.
 Since version 2016h, each release has contained a text file named
-"<samp>version</samp>" whose first (and currently only) line is the version.
+"<code>version</code>" whose first (and currently only) line is the version.
 Older releases are <a href="https://ftp.iana.org/tz/releases/">archived</a>,
 and are also available in an
 <a href="ftp://ftp.iana.org/tz/releases/"><abbr
@@ -362,9 +362,6 @@ <h2 id="web">Web sites using recent versions of the
 <li><a
 href="https://www.convertit.com/Go/ConvertIt/World_Time/Current_Time.ASP">Current
 Time in 1000 Places</a> uses descriptions of the values.</li>
-<li><a href="https://home.kpn.nl/vanadovv/time/TZworld.html">Complete
-timezone information for all countries</a>
-displays tables of <abbr>DST</abbr> rules.
 <li><a href="https://www.timeanddate.com/worldclock/">The World Clock &ndash;
 Worldwide</a> lets you sort zone names and convert times.</li>
 <li><a href="https://24timezones.com">24TimeZones</a> has a world
@@ -511,12 +508,12 @@ <h2 id="compilers">Other <code><abbr>tz</abbr></code> compilers</h2>
 <li>Many modern
 <a href="https://en.wikipedia.org/wiki/JavaScript">JavaScript</a>
 runtimes support <code><abbr>tz</abbr></code> natively via the
-<samp>timeZone</samp> option of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat"><samp>Intl.DateTimeFormat</samp></a>.
+<code>timeZone</code> option of <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat"><code>Intl.DateTimeFormat</code></a>.
 This can be used as-is or with most of the following libraries,
-many of which also support runtimes lacking the <samp>timeZone</samp> option.
+many of which also support runtimes lacking the <code>timeZone</code> option.
 <ul>
 <li>The <a
-href="https://github.com/formatjs/date-time-format-timezone"><samp>Intl.DateTimeFormat</samp>
+href="https://github.com/formatjs/date-time-format-timezone"><code>Intl.DateTimeFormat</code>
 timezone polyfill</a>
 is freely available under a <abbr>BSD</abbr>-style license.</li>
 <li>The <a href="https://date-fns.org/">date-fns</a>
@@ -529,7 +526,7 @@ <h2 id="compilers">Other <code><abbr>tz</abbr></code> compilers</h2>
 manipulation library.
 It is freely available under the <abbr>MIT</abbr> license.</li>
 <li><a href="https://moment.github.io/luxon/">Luxon</a> improves
-timezone support for the <samp>Intl</samp> API.
+timezone support for the <code>Intl</code> API.
 It is freely available under the <abbr>MIT</abbr> license.</li>
 <li><a href="https://momentjs.com/timezone/">Moment Timezone</a> is a
 Moment.js plugin.
@@ -550,11 +547,11 @@ <h2 id="compilers">Other <code><abbr>tz</abbr></code> compilers</h2>
 It is freely available under the <abbr>MIT</abbr> license.</li>
 </ul>
 The proposed <a
-href="https://github.com/tc39/proposal-temporal"><samp>Temporal</samp>
+href="https://github.com/tc39/proposal-temporal"><code>Temporal</code>
 objects</a> let programs access an abstract view of
 <code><abbr>tzdb</abbr></code> data, and are designed to replace <a
 href="https://codeofmatt.com/javascript-date-type-is-horribly-broken/">JavaScript's
-problematic <samp>Date</samp> objects</a> when working with dates and times.
+problematic <code>Date</code> objects</a> when working with dates and times.
 <li><a href="https://github.com/JuliaTime/">JuliaTime</a> contains a
 compiler from <code><abbr>tz</abbr></code> source into
 <a href="https://julialang.org/">Julia</a>. It is freely available
@@ -620,6 +617,16 @@ <h2 id="TZif">Other <abbr>TZif</abbr> readers</h2>
 library that translates between <abbr>UT</abbr> and civil time and
 can read <abbr>TZif</abbr> files. It is freely available under the Apache
 License.</li>
+<li>The
+<a href="https://github.com/nayarsystems/posix_tz_db"><code>posix_tz_db</code>
+package</a> contains Python code
+to generate <abbr>CSV</abbr> and <abbr>JSON</abbr> tables that map
+<code><abbr>tz</abbr></code> settings to POSIX.1-2017-like approximations.
+For example, it maps <code>"Africa/Cairo"</code>
+to <code>"EET-2EEST,M4.5.5/0,M10.5.4/24"</code>,
+an approximation valid for Cairo timestamps from 2023 on.
+This can help porting to platforms that support only POSIX.1-2017.
+The package is freely available under the MIT license.</li>
 <li><a href="https://github.com/derickr/timelib">Timelib</a> is a C
 library that reads <abbr>TZif</abbr> files and converts
 timestamps from one time zone or format to another.
@@ -666,9 +673,7 @@ <h2 id="software">Other <code><abbr>tz</abbr></code>-based time zone software</h
 <ul>
 <li><a href="https://foxclocks.org">FoxClocks</a>
 is an extension for <a href="https://www.google.com/chrome/">Google
-Chrome</a> and for <a
-href="https://wiki.mozilla.org/Modules/Toolkit">Mozilla
-Toolkit</a> applications like <a
+Chrome</a>, <a
 href="https://www.mozilla.org/en-US/firefox/new/">Firefox</a> and <a
 href="https://www.mozilla.org/en-US/thunderbird/">Thunderbird</a>.
 It displays multiple clocks in the application window, and has a mapping
@@ -782,32 +787,9 @@ <h2 id="boundaries">Time zone boundaries</h2>
 Its code is freely available under the <abbr>MIT</abbr> license, and
 its data entries are freely available under the
 <a href="https://opendatacommons.org/licenses/odbl/">Open Data Commons
-Open Database License</a>. The maps' borders appear to be quite accurate.</li>
-<li>Programmatic interfaces that map geographical coordinates via tz_world to
-<code><abbr>tzdb</abbr></code> timezones include:
-<ul>
-<li><a href="https://github.com/mj1856/GeoTimeZone">GeoTimeZone</a> is
-written in <a
-href="https://en.wikipedia.org/wiki/C_Sharp_(programming_language)">C#</a>
-and is freely available under the <abbr>MIT</abbr> license.</li>
-<li>The <a href="https://github.com/bradfitz/latlong">latlong package</a>
-is written in Go and is freely available under the Apache License.</li>
-<li><a href="https://github.com/drtimcooper/LatLongToTimezone">LatLongToTimezone</a>,
-in both Java and
-<a href="https://en.wikipedia.org/wiki/Swift_(programming_language)">Swift</a>
-form, is freely available under the MIT license.</li>
-<li>For Node.js,
-the <a href="https://www.npmjs.com/package/geo-tz">geo-tz module</a>
-is freely available under the MIT license, and
-the <a href="https://www.npmjs.com/package/tz-lookup">tz-lookup module</a>
-is in the public domain.</li>
-<li>The <a
-href="https://github.com/MrMinimal64/timezonefinder">timezonefinder</a>
-library for Python is freely available under the MIT license.
-<li>The <a
-href="https://github.com/gunyarakun/timezone_finder">timezone_finder</a>
-library for Ruby is freely available under the MIT license.</li>
-</ul></li>
+Open Database License</a>. The borders appear to be quite accurate.
+Its main web page lists more than twenty libraries
+for looking up a timezone name from a GPS coordinate.</li>
 <li>Free access via a network API, if you register a key, is provided by
 the <a
 href="https://www.geonames.org/export/web-services.html#timezone">GeoNames
@@ -826,12 +808,9 @@ <h2 id="boundaries">Time zone boundaries</h2>
 <li><a href="http://statoids.com/statoids.html">Administrative
 Divisions of Countries ("Statoids")</a> lists
 political subdivision data related to time zones.</li>
-<li><a href="https://home.kpn.nl/vanadovv/time/Multizones.html">Time
-zone boundaries for multizone countries</a> summarizes legal
-boundaries between time zones within countries.</li>
 <li><a href="https://manifold.net/info/freestuff.shtml">Manifold Software
 &ndash; GIS and Database Tools</a> includes a Manifold-format map of
-world time zone boundaries distributed under the
+world time zone boundaries circa 2007, distributed under the
 <abbr>GPL</abbr>.</li>
 <li>A ship within the <a
 href="https://en.wikipedia.org/wiki/Territorial_waters">territorial
@@ -862,7 +841,7 @@ <h2 id="civil">Civil time concepts and history</h2>
 <li><a href="https://www.w3.org/TR/timezone/">Working with Time Zones</a>
 contains guidelines and best practices for software applications that
 deal with civil time.</li>
-<li><a href="https://www.staff.science.uu.nl/~gent0113/idl/idl.htm">A History of
+<li><a href="https://webspace.science.uu.nl/~gent0113/idl/idl.htm">A History of
 the International Date Line</a> tells the story of the most important
 time zone boundary.</li>
 <li><a href="http://statoids.com/tconcept.html">Basic Time
@@ -875,17 +854,17 @@ <h2 id="national">National histories of legal time</h2>
 <dl>
 <dt>Australia</dt>
 <dd>The Parliamentary Library commissioned a <a
-href="https://www.aph.gov.au/binaries/library/pubs/rp/2009-10/10rp10.pdf">research
+href="https://parlinfo.aph.gov.au/parlInfo/download/library/prspub/359V6/upload_binary/359v60.pdf">research
 paper on daylight saving time in Australia</a>.
 The Bureau of Meteorology publishes a list of <a
 href="http://www.bom.gov.au/climate/averages/tables/dst_times.shtml">Implementation
 Dates of Daylight Savings Time within Australia</a>.</dd>
 <dt>Belgium</dt>
 <dd>The Royal Observatory of Belgium maintains a table of time in
 Belgium (in
-<a href="https://www.astro.oma.be/GENERAL/INFO/nli001a.html"
+<a href="https://robinfo.oma.be/nl/astro-info/tijd/"
 hreflang="nl">Dutch</a> and <a
-href="https://www.astro.oma.be/GENERAL/INFO/fri001a.html"
+href="https://robinfo.oma.be/fr/astro-info/heure/"
 hreflang="fr">French</a>).</dd>
 <dt>Brazil</dt>
 <dd>The Time Service Department of the National Observatory
@@ -929,7 +908,7 @@ <h2 id="national">National histories of legal time</h2>
 href="https://www.diputados.gob.mx/bibliot/publica/inveyana/polisoc/horver/index.htm"
 hreflang="es">history of Mexican local time (in Spanish)</a>.</dd>
 <dt>Netherlands</dt>
-<dd><a href="https://www.staff.science.uu.nl/~gent0113/wettijd/wettijd.htm"
+<dd><a href="https://webspace.science.uu.nl/~gent0113/wettijd/wettijd.htm"
 hreflang="nl">Legal time in the Netherlands (in Dutch)</a>
 covers the history of local time in the Netherlands from ancient times.</dd>
 <dt>New Zealand</dt>
@@ -938,7 +917,7 @@ <h2 id="national">National histories of legal time</h2>
 Daylight Saving</a>.</dd>
 <dt>Palestine</dt>
 <dd>The Ministry of Telecom and IT publishes a <a
-href="https://mtit.pna.ps/Site/TimeZoon"
+href="https://mtit.pna.ps/home/TimeZone"
 hreflang="ar">history of clock changes (in Arabic)</a>.</dd>
 <dt>Portugal</dt>
 <dd>The Lisbon Astronomical Observatory publishes a
@@ -986,14 +965,17 @@ <h2 id="costs">Costs and benefits of time shifts</h2>
 shifts in time zones.</li>
 <li>Havranek T, Herman D, Irsova D.
 <a href="https://www.iaee.org/en/publications/ejarticle.aspx?id=3051">Does
-daylight saving save electricity? A meta-analysis.</a>
+daylight saving save electricity? A meta-analysis</a>.
 <em>Energy J.</em> 2018;39(2):35&ndash;61.
 doi:<a href="https://doi.org/10.5547/01956574.39.2.thav">10.5547/01956574.39.2.thav</a>.
 This analyzes research literature and concludes, "Electricity savings
 are larger for countries farther away from the equator, while
 subtropical regions consume more electricity because of <abbr>DST</abbr>."</li>
-<li>Malow BA. It is time to abolish the clock change and adopt permanent
-standard time in the United States: a Sleep Research Society position statement.
+<li>Malow BA. <a
+href="https://academic.oup.com/sleep/article/45/12/zsac236/6717940">It is time
+to abolish the clock change and adopt permanent
+standard time in the United States:
+a Sleep Research Society position statement</a>.
 <em>Sleep.</em> 2022;45(12):zsac236.
 doi:<a href="https://doi.org/10.1093/sleep/zsac236">10.1093/sleep/zsac236</a>.
 After reviewing the scientific literature, the Sleep Research Society
@@ -1002,13 +984,13 @@ <h2 id="costs">Costs and benefits of time shifts</h2>
 <a href="https://jcsm.aasm.org/doi/10.5664/jcsm.10898">Permanent standard time
 is the optimal choice for health and safety:
 an American Academy of Sleep Medicine position statement</a>.
-<em>J Clin Sleep Med.</em> 2023-10-31.
+<em>J Clin Sleep Med.</em> 2024;20(1):121&ndash;125.
 doi:<a href="https://doi.org/10.5664/jcsm.10898">10.5664/jcsm.10898</a>.
 The AASM argues for permanent standard time due to health and safety risks
 and economic costs of both <abbr>DST</abbr> transitions and
 permanent <abbr>DST</abbr>.</li>
 <li>Roenneberg T, Wirz-Justice A, Skene DJ <em>et al</em>.
-<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7205184/">Why
+<a href="https://journals.sagepub.com/doi/10.1177/0748730419854197">Why
 should we abolish Daylight Saving Time?</a>
 <em>J Biol Rhythms.</em> 2019;34(3):227&ndash;230.
 doi:<a href="https://doi.org/10.1177/0748730419854197">10.1177/0748730419854197</a>.
@@ -1128,9 +1110,12 @@ <h2 id="precision">Precision timekeeping</h2>
 without Leap Seconds</a> gives pointers on this
 contentious issue.
 The General Conference on Weights and Measures
-<a href="https://www.bipm.org/en/cgpm-2022/resolution-4">voted in 2022</a>
+<a href="https://www.bipm.org/en/cgpm-2022/resolution-4">decided in 2022</a>
 to discontinue the use of leap seconds by 2035, replacing them with an
 as-yet-undetermined scheme some time after the year 2135.
+The World Radiocommunication Conference <a
+href="https://www.itu.int/dms_pub/itu-r/opb/act/R-ACT-WRC.15-2023-PDF-E.pdf">resolved
+in 2023</a> to cooperate with this process.
 </li>
 </ul>
 </section>

diff --git a/tzfile.5 b/tzfile.5
@@ -85,7 +85,7 @@ described in the file is associated with the time period
 starting with the same-indexed transition time
 and continuing up to but not including the next transition time.
 (The last time type is present only for consistency checking with the
-POSIX-style TZ string described below.)
+POSIX.1-2017-style TZ string described below.)
 These values serve as indices into the next field.
 .IP \(bu
 .B tzh_typecnt
@@ -186,7 +186,8 @@ must also be set.
 .PP
 The standard/wall and UT/local indicators were designed for
 transforming a TZif file's transition times into transitions appropriate
-for another time zone specified via a POSIX-style TZ string that lacks rules.
+for another time zone specified via
+a POSIX.1-2017-style TZ string that lacks rules.
 For example, when TZ="EET\*-2EEST" and there is no TZif file "EET\*-2EEST",
 the idea was to adapt the transition times from a TZif file with the
 well-known name "posixrules" that is present only for this purpose and
@@ -215,13 +216,14 @@ the above header and data are followed by a second header and data,
 identical in format except that
 eight bytes are used for each transition time or leap second time.
 (Leap second counts remain four bytes.)
-After the second header and data comes a newline-enclosed,
-POSIX-TZ-environment-variable-style string for use in handling instants
+After the second header and data comes a newline-enclosed string
+in the style of the contents of a POSIX.1-2017 TZ environment variable,
+for use in handling instants
 after the last transition time stored in the file
 or for all instants if the file has no transitions.
-The POSIX-style TZ string is empty (i.e., nothing between the newlines)
-if there is no POSIX-style representation for such instants.
-If nonempty, the POSIX-style TZ string must agree with the local time
+The TZ string is empty (i.e., nothing between the newlines)
+if there is no POSIX.1-2017-style representation for such instants.
+If nonempty, the TZ string must agree with the local time
 type after the last transition time if present in the eight-byte data;
 for example, given the string
 .q "WET0WEST,M3.5.0/1,M10.5.0"
@@ -233,8 +235,8 @@ Also, if there is at least one transition, time type 0 is associated
 with the time period from the indefinite past up to but not including
 the earliest transition time.
 .SS Version 3 format
-For version-3-format timezone files, the POSIX-TZ-style string may
-use two minor extensions to the POSIX TZ format, as described in
+For version-3-format timezone files, the TZ string may
+use two minor extensions to the POSIX.1-2017 TZ format, as described in
 .BR newtzset (3).
 First, the hours part of its transition times may be signed and range from
 \-167 through 167 instead of the POSIX-required unsigned values
@@ -352,7 +354,7 @@ version 2+ data even if the reader's native timestamps have only
 .IP \(bu
 Some readers designed for version 2 might mishandle
 timestamps after a version 3 or higher file's last transition, because
-they cannot parse extensions to POSIX in the TZ-like string.
+they cannot parse extensions to POSIX.1-2017 in the TZ-like string.
 As a partial workaround, a writer can output more transitions
 than necessary, so that only far-future timestamps are
 mishandled by version 2 readers.
@@ -403,7 +405,7 @@ Some readers mishandle a transition if its timestamp has
 the minimum possible signed 64-bit value.
 Timestamps less than \-2**59 are not recommended.
 .IP \(bu
-Some readers mishandle POSIX-style TZ strings that
+Some readers mishandle TZ strings that
 contain
 .q "<"
 or
@@ -431,12 +433,12 @@ Some readers mishandle TZif files that specify
 daylight-saving time UT offsets that are less than the UT
 offsets for the corresponding standard time.
 These readers do not support locations like Ireland, which
-uses the equivalent of the POSIX TZ string
+uses the equivalent of the TZ string
 .q "IST\*-1GMT0,M10.5.0,M3.5.0/1",
 observing standard time
 (IST, +01) in summer and daylight saving time (GMT, +00) in winter.
 As a partial workaround, a writer can output data for the
-equivalent of the POSIX TZ string
+equivalent of the TZ string
 .q "GMT0IST,M3.5.0/1,M10.5.0",
 thus swapping standard and daylight saving time.
 Although this workaround misidentifies which part of the year

diff --git a/tzfile.h b/tzfile.h
@@ -78,11 +78,11 @@ struct tzhead {
 ** time uses 8 rather than 4 chars,
 ** then a POSIX-TZ-environment-variable-style string for use in handling
 ** instants after the last transition time stored in the file
-** (with nothing between the newlines if there is no POSIX representation for
-** such instants).
+** (with nothing between the newlines if there is no POSIX.1-2017
+** representation for such instants).
 **
 ** If tz_version is '3' or greater, the above is extended as follows.
-** First, the POSIX TZ string's hour offset may range from -167
+** First, the TZ string's hour offset may range from -167
 ** through 167 as compared to the POSIX-required 0 through 24.
 ** Second, its DST start time may be January 1 at 00:00 and its stop
 ** time December 31 at 24:00 plus the difference between DST and

diff --git a/tzselect.ksh b/tzselect.ksh
@@ -40,9 +40,13 @@ REPORT_BUGS_TO=tz@iana.org
 # The substr avoids problems when VALUE is of the form X=Y and would be
 # misinterpreted as an assignment.
 
+# This script does not want path expansion.
+set -f
+
 # Specify default values for environment variables if they are unset.
 : ${AWK=awk}
-: ${TZDIR=`pwd`}
+: ${PWD=`pwd`}
+: ${TZDIR=$PWD}
 
 # Output one argument as-is to standard output, with trailing newline.
 # Safer than 'echo', which can mishandle '\' or leading '-'.
@@ -113,7 +117,8 @@ then
 else
   doselect() {
     # Field width of the prompt numbers.
-    select_width=`expr $# : '.*'`
+    print_nargs_length="BEGIN {print length(\"$#\");}"
+    select_width=`$AWK "$print_nargs_length"`
 
     select_i=
 
@@ -124,14 +129,14 @@ else
 	select_i=0
 	for select_word
 	do
-	  select_i=`expr $select_i + 1`
+	  select_i=`$AWK "BEGIN { print $select_i + 1 }"`
 	  printf >&2 "%${select_width}d) %s\\n" $select_i "$select_word"
 	done;;
       *[!0-9]*)
 	echo >&2 'Please enter a number in range.';;
       *)
 	if test 1 -le $select_i && test $select_i -le $#; then
-	  shift `expr $select_i - 1`
+	  shift `$AWK "BEGIN { print $select_i - 1 }"`
 	  select_result=$1
 	  break
 	fi
@@ -165,7 +170,7 @@ do
   esac
 done
 
-shift `expr $OPTIND - 1`
+shift `$AWK "BEGIN { print $OPTIND - 1 }"`
 case $# in
 0) ;;
 *) say >&2 "$0: $1: unknown argument"; exit 1
@@ -433,13 +438,18 @@ while
     eval '
       doselect '"$quoted_continents"' \
 	"coord - I want to use geographical coordinates." \
-	"TZ - I want to specify the timezone using the POSIX TZ format." \
+	"TZ - I want to specify the timezone using a POSIX.1-2017 TZ string." \
 	"time - I know local time already." \
 	"now - Like \"time\", but configure only for timestamps from now on."
       continent=$select_result
       case $continent in
       Americas) continent=America;;
-      *" "*)    continent=`expr "$continent" : '\''\([^ ]*\)'\''`
+      *)
+	# Get the first word of $continent.  Path expansion is disabled
+	# so this works even with "*", which should not happen.
+	IFS=" "
+	for continent in $continent ""; do break; done
+	IFS=$newline;;
       esac
       case $zonetabtype,$continent in
       zonenow,*) ;;
@@ -452,7 +462,7 @@ while
 
   case $continent in
   TZ)
-    # Ask the user for a POSIX TZ string.  Check that it conforms.
+    # Ask the user for a POSIX.1-2017 TZ string.  Check that it conforms.
     check_POSIX_TZ_string='
       BEGIN {
 	tz = substr(ARGV[1], 2)
@@ -482,7 +492,7 @@ while
       read tz
       $AWK "$check_POSIX_TZ_string" ="$tz"
     do
-      say >&2 "'$tz' is not a conforming POSIX timezone string."
+      say >&2 "'$tz' is not a conforming POSIX.1-2017 timezone string."
     done
     TZ_for_date=$tz;;
   *)
@@ -502,7 +512,7 @@ while
 	  "$output_distances_or_times" \
 	  ="$coord" ="$TZ_COUNTRY_TABLE" ="$TZ_ZONE_TABLE" |
 	sort -n |
-	sed "${location_limit}q"
+	$AWK "{print} NR == $location_limit { exit }"
       `
       regions=`
 	$AWK '
@@ -746,15 +756,18 @@ while
   do
     TZdate=`LANG=C TZ="$TZ_for_date" date`
     UTdate=`LANG=C TZ=UTC0 date`
-    TZsec=`expr "$TZdate" : '.*:\([0-5][0-9]\)'`
-    UTsec=`expr "$UTdate" : '.*:\([0-5][0-9]\)'`
-    case $TZsec in
-    $UTsec)
+    if $AWK '
+	  function getsecs(d) {
+	    return match(d, /.*:[0-5][0-9]/) ? substr(d, RLENGTH - 1, 2) : ""
+	  }
+	  BEGIN { exit getsecs(ARGV[1]) != getsecs(ARGV[2]) }
+       ' ="$TZdate" ="$UTdate"
+    then
       extra_info="
 Selected time is now:	$TZdate.
 Universal Time is now:	$UTdate."
       break
-    esac
+    fi
   done
 
 

diff --git a/zic.8 b/zic.8
@@ -171,7 +171,7 @@ boundaries, particularly if
 causes a TZif file to contain explicit entries for
 .RI pre- hi
 transitions rather than concisely representing them
-with an extended POSIX TZ string.
+with an extended POSIX.1-2017 TZ string.
 Also see the
 .B "\*-b slim"
 option for another way to shrink output size.
@@ -181,10 +181,10 @@ Generate redundant trailing explicit transitions for timestamps
 that occur less than
 .I hi
 seconds since the Epoch, even though the transitions could be
-more concisely represented via the extended POSIX TZ string.
+more concisely represented via the extended POSIX.1-2017 TZ string.
 This option does not affect the represented timestamps.
 Although it accommodates nonstandard TZif readers
-that ignore the extended POSIX TZ string,
+that ignore the extended POSIX.1-2017 TZ string,
 it increases the size of the altered output files.
 .TP
 .BI "\*-t " file
@@ -245,10 +245,10 @@ for
 .PP
 The output file does not contain all the information about the
 long-term future of a timezone, because the future cannot be summarized as
-an extended POSIX TZ string.  For example, as of 2023 this problem
+an extended POSIX.1-2017 TZ string.  For example, as of 2023 this problem
 occurs for Morocco's daylight-saving rules, as these rules are based
 on predictions for when Ramadan will be observed, something that
-an extended POSIX TZ string cannot represent.
+an extended POSIX.1-2017 TZ string cannot represent.
 .PP
 The output contains data that may not be handled properly by client
 code designed for older
@@ -360,24 +360,15 @@ an unquoted name should not contain characters from the set
 Gives the first year in which the rule applies.
 Any signed integer year can be supplied; the proleptic Gregorian calendar
 is assumed, with year 0 preceding year 1.
-The word
-.B minimum
-(or an abbreviation) means the indefinite past.
-The word
-.B maximum
-(or an abbreviation) means the indefinite future.
 Rules can describe times that are not representable as time values,
 with the unrepresentable times ignored; this allows rules to be portable
 among hosts with differing time value types.
 .TP
 .B TO
 Gives the final year in which the rule applies.
-In addition to
-.B minimum
-and
+The word
 .B maximum
-(as above),
-the word
+(or an abbreviation) means the indefinite future, and the word
 .B only
 (or an abbreviation)
 may be used to repeat the value of the

diff --git a/zic.c b/zic.c
@@ -35,6 +35,9 @@ static zic_t const
 # define ZIC_MAX_ABBR_LEN_WO_WARN 6
 #endif /* !defined ZIC_MAX_ABBR_LEN_WO_WARN */
 
+/* Minimum and maximum years, assuming signed 32-bit time_t.  */
+enum { YEAR_32BIT_MIN = 1901, YEAR_32BIT_MAX = 2038 };
+
 /* An upper bound on how much a format might grow due to concatenation.  */
 enum { FORMAT_LEN_GROWTH_BOUND = 5 };
 
@@ -93,7 +96,6 @@ struct rule {
 
 	zic_t		r_loyear;	/* for example, 1986 */
 	zic_t		r_hiyear;	/* for example, 1986 */
-	bool		r_lowasnum;
 	bool		r_hiwasnum;
 
 	int		r_month;	/* 0..11 */
@@ -328,7 +330,7 @@ enum {
 */
 
 enum {
-  YR_MINIMUM,
+  YR_MINIMUM, /* "minimum" is for backward compatibility only */
   YR_MAXIMUM,
   YR_ONLY
 };
@@ -412,12 +414,10 @@ static struct lookup const	lasts[] = {
 
 static struct lookup const	begin_years[] = {
 	{ "minimum",	YR_MINIMUM },
-	{ "maximum",	YR_MAXIMUM },
 	{ NULL,		0 }
 };
 
 static struct lookup const	end_years[] = {
-	{ "minimum",	YR_MINIMUM },
 	{ "maximum",	YR_MAXIMUM },
 	{ "only",	YR_ONLY },
 	{ NULL,		0 }
@@ -2187,13 +2187,12 @@ rulesub(struct rule *rp, const char *loyearp, const char *hiyearp,
 	*/
 	cp = loyearp;
 	lp = byword(cp, begin_years);
-	rp->r_lowasnum = lp == NULL;
-	if (!rp->r_lowasnum) switch (lp->l_value) {
+	if (lp) switch (lp->l_value) {
 		case YR_MINIMUM:
-			rp->r_loyear = ZIC_MIN;
-			break;
-		case YR_MAXIMUM:
-			rp->r_loyear = ZIC_MAX;
+			warning(_("FROM year \"%s\" is obsolete;"
+				  " treated as %d"),
+				cp, YEAR_32BIT_MIN - 1);
+			rp->r_loyear = YEAR_32BIT_MIN - 1;
 			break;
 		default: unreachable();
 	} else if (sscanf(cp, "%"SCNdZIC"%c", &rp->r_loyear, &xs) != 1) {
@@ -2204,9 +2203,6 @@ rulesub(struct rule *rp, const char *loyearp, const char *hiyearp,
 	lp = byword(cp, end_years);
 	rp->r_hiwasnum = lp == NULL;
 	if (!rp->r_hiwasnum) switch (lp->l_value) {
-		case YR_MINIMUM:
-			rp->r_hiyear = ZIC_MIN;
-			break;
 		case YR_MAXIMUM:
 			rp->r_hiyear = ZIC_MAX;
 			break;
@@ -2986,7 +2982,7 @@ rule_cmp(struct rule const *a, struct rule const *b)
 	return a->r_dayofmonth - b->r_dayofmonth;
 }
 
-/* Store into RESULT a POSIX TZ string that represent the future
+/* Store into RESULT a POSIX.1-2017 TZ string that represent the future
    predictions for the zone ZPFIRST with ZONECOUNT entries.  Return a
    compatibility indicator (a TZDB release year) if successful, a
    negative integer if no such TZ string exissts.  */
@@ -3125,7 +3121,6 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 	register char *			envvar;
 	register int			max_abbr_len;
 	register int			max_envvar_len;
-	register bool			prodstic; /* all rules are min to max */
 	register int			compat;
 	register bool			do_extend;
 	register char			version;
@@ -3151,7 +3146,6 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 	timecnt = 0;
 	typecnt = 0;
 	charcnt = 0;
-	prodstic = zonecount == 1;
 	/*
 	** Thanks to Earl Chew
 	** for noting the need to unconditionally initialize startttisstd.
@@ -3169,12 +3163,9 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 			updateminmax(zp->z_untilrule.r_loyear);
 		for (j = 0; j < zp->z_nrules; ++j) {
 			struct rule *rp = &zp->z_rules[j];
-			if (rp->r_lowasnum)
-				updateminmax(rp->r_loyear);
+			updateminmax(rp->r_loyear);
 			if (rp->r_hiwasnum)
 				updateminmax(rp->r_hiyear);
-			if (rp->r_lowasnum || rp->r_hiwasnum)
-				prodstic = false;
 		}
 	}
 	/*
@@ -3186,7 +3177,8 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 	if (noise) {
 		if (!*envvar)
 			warning("%s %s",
-				_("no POSIX environment variable for zone"),
+				_("no POSIX.1-2017 environment variable"
+				  " for zone"),
 				zpfirst->z_name);
 		else if (compat != 0) {
 			/* Circa-COMPAT clients, and earlier clients, might
@@ -3198,48 +3190,23 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 		}
 	}
 	if (do_extend) {
-		/*
-		** Search through a couple of extra years past the obvious
-		** 400, to avoid edge cases.  For example, suppose a non-POSIX
-		** rule applies from 2012 onwards and has transitions in March
-		** and September, plus some one-off transitions in November
-		** 2013.  If zic looked only at the last 400 years, it would
-		** set max_year=2413, with the intent that the 400 years 2014
-		** through 2413 will be repeated.  The last transition listed
-		** in the tzfile would be in 2413-09, less than 400 years
-		** after the last one-off transition in 2013-11.  Two years
-		** might be overkill, but with the kind of edge cases
-		** available we're not sure that one year would suffice.
-		*/
-		enum { years_of_observations = YEARSPERREPEAT + 2 };
-
 		if (min_year >= ZIC_MIN + years_of_observations)
 			min_year -= years_of_observations;
 		else	min_year = ZIC_MIN;
 		if (max_year <= ZIC_MAX - years_of_observations)
 			max_year += years_of_observations;
 		else	max_year = ZIC_MAX;
-		/*
-		** Regardless of any of the above,
-		** for a "proDSTic" zone which specifies that its rules
-		** always have and always will be in effect,
-		** we only need one cycle to define the zone.
-		*/
-		if (prodstic) {
-			min_year = 1900;
-			max_year = min_year + years_of_observations;
-		}
 	}
 	max_year = max(max_year, (redundant_time / (SECSPERDAY * DAYSPERNYEAR)
 				  + EPOCH_YEAR + 1));
 	max_year0 = max_year;
 	if (want_bloat()) {
 	  /* For the benefit of older systems,
 	     generate data from 1900 through 2038.  */
-	  if (min_year > 1900)
-		min_year = 1900;
-	  if (max_year < 2038)
-		max_year = 2038;
+	  if (min_year > YEAR_32BIT_MIN - 1)
+		min_year = YEAR_32BIT_MIN - 1;
+	  if (max_year < YEAR_32BIT_MAX)
+		max_year = YEAR_32BIT_MAX;
 	}
 
 	if (min_time < lo_time || hi_time < max_time)
@@ -3474,8 +3441,8 @@ outzone(const struct zone *zpfirst, ptrdiff_t zonecount)
 	}
 	if (do_extend) {
 		/*
-		** If we're extending the explicitly listed observations
-		** for 400 years because we can't fill the POSIX-TZ field,
+		** If we're extending the explicitly listed observations for
+		** 400 years because we can't fill the POSIX.1-2017 TZ field,
 		** check whether we actually ended up explicitly listing
 		** observations through that period.  If there aren't any
 		** near the end of the 400-year period, add a redundant

diff --git a/zishrink.awk b/zishrink.awk
@@ -162,7 +162,7 @@ function make_line(n, field, \
 # Process the input line LINE and save it for later output.
 
 function process_input_line(line, \
-			    f, field, end, i, n, r, startdef, \
+			    f, field, end, n, outline, r, \
 			    linkline, ruleline, zoneline)
 {
   # Remove comments, normalize spaces, and append a space to each line.
@@ -199,8 +199,10 @@ function process_input_line(line, \
   }
 
   # Abbreviate "max", "min", "only" and month names.
-  gsub(/ max /, " ma ", line)
-  gsub(/ min /, " mi ", line)
+  # Although "max" and "min" can both be abbreviated to just "m",
+  # the longer forms "ma" and "mi" are needed with zic 2023d and earlier.
+  gsub(/ max /, dataform == "vanguard" ? " m " : " ma ", line)
+  gsub(/ min /, dataform == "vanguard" ? " m " : " mi ", line)
   gsub(/ only /, " o ", line)
   gsub(/ Jan /, " Ja ", line)
   gsub(/ Feb /, " F ", line)
@@ -234,66 +236,96 @@ function process_input_line(line, \
     rule_used[r] = 1
   }
 
-  # If this zone supersedes an earlier one, delete the earlier one
-  # from the saved output lines.
-  startdef = ""
   if (zoneline)
     zonename = startdef = field[2]
   else if (linkline)
     zonename = startdef = field[3]
   else if (ruleline)
     zonename = ""
-  if (startdef) {
-    i = zonedef[startdef]
-    if (i) {
-      do
-	output_line[i - 1] = ""
-      while (output_line[i++] ~ /^[-+0-9]/);
-    }
-  }
-  zonedef[zonename] = nout + 1
 
-  # Save the line for later output.
-  output_line[nout++] = make_line(n, field)
+  # Save the information for later output.
+  outline = make_line(n, field)
+  if (ruleline)
+    rule_output_line[nrule_out++] = outline
+  else if (linkline) {
+    # In vanguard format with Gawk, links are output sorted by destination.
+    if (dataform == "vanguard" && PROCINFO["version"])
+      linkdef[zonename] = field[2]
+    else
+      link_output_line[nlink_out++] = outline
+  }else
+    zonedef[zonename] = (zoneline ? "" : zonedef[zonename] "\n") outline
 }
 
 function omit_unused_rules( \
 			   i, field)
 {
-  for (i = 0; i < nout; i++) {
-    split(output_line[i], field)
-    if (field[1] == "R" && !rule_used[field[2]]) {
-      output_line[i] = ""
-    }
+  for (i = 0; i < nrule_out; i++) {
+    split(rule_output_line[i], field)
+    if (!rule_used[field[2]])
+      rule_output_line[i] = ""
   }
 }
 
 function abbreviate_rule_names( \
-			       abbr, f, field, i, n, r)
+			       abbr, f, field, i, n, newdef, newline, r, \
+			       zoneline, zonelines, zonename)
 {
-  for (i = 0; i < nout; i++) {
-    n = split(output_line[i], field)
+  for (i = 0; i < nrule_out; i++) {
+    n = split(rule_output_line[i], field)
     if (n) {
-      f = field[1] == "Z" ? 4 : field[1] == "L" ? 0 : 2
-      r = field[f]
+      r = field[2]
       if (r ~ /^[^-+0-9]/) {
 	abbr = rule[r]
 	if (!abbr) {
 	  rule[r] = abbr = gen_rule_name(r)
 	}
-	field[f] = abbr
-	output_line[i] = make_line(n, field)
+	field[2] = abbr
+	rule_output_line[i] = make_line(n, field)
       }
     }
   }
+  for (zonename in zonedef) {
+    zonelines = split(zonedef[zonename], zoneline, /\n/)
+    newdef = ""
+    for (i = 1; i <= zonelines; i++) {
+      newline = zoneline[i]
+      n = split(newline, field)
+      f = i == 1 ? 4 : 2
+      r = rule[field[f]]
+      if (r) {
+	field[f] = r
+	newline = make_line(n, field)
+      }
+      newdef = (newdef ? newdef "\n" : "") newline
+    }
+    zonedef[zonename] = newdef
+  }
 }
 
 function output_saved_lines( \
-			    i)
+			    i, zonename)
 {
-  for (i = 0; i < nout; i++)
-    if (output_line[i])
-      print output_line[i]
+  for (i = 0; i < nrule_out; i++)
+    if (rule_output_line[i])
+      print rule_output_line[i]
+
+  # When using gawk, output zones sorted by name.
+  # This makes the output a bit more compressible.
+  PROCINFO["sorted_in"] = "@ind_str_asc"
+  for (zonename in zonedef)
+    print zonedef[zonename]
+
+  if (nlink_out)
+    for (i = 0; i < nlink_out; i++)
+      print link_output_line[i]
+  else {
+    # When using gawk, output links sorted by destination.
+    # This also helps compressibility a bit.
+    PROCINFO["sorted_in"] = "@val_type_asc"
+    for (zonename in linkdef)
+      printf "L %s %s\n", linkdef[zonename], zonename
+  }
 }
 
 BEGIN {

diff --git a/zonenow.tab b/zonenow.tab
@@ -199,7 +199,7 @@ XX	+2518+05518	Asia/Dubai	Russia; Caucasus; Persian Gulf; Seychelles; Réunion
 XX	+3431+06912	Asia/Kabul	Afghanistan
 #
 # +05
-XX	+4120+06918	Asia/Tashkent	Russia; Tajikistan; Turkmenistan; Uzbekistan; Maldives
+XX	+4120+06918	Asia/Tashkent	Russia; west Kazakhstan; Tajikistan; Turkmenistan; Uzbekistan; Maldives
 #
 # +05 - PKT
 XX	+2452+06703	Asia/Karachi	Pakistan ("PKT")
@@ -215,6 +215,8 @@ XX	+2743+08519	Asia/Kathmandu	Nepal
 #
 # +06
 XX	+2343+09025	Asia/Dhaka	Russia; Kyrgyzstan; Bhutan; Bangladesh; Chagos
+# +06 until 2024-03-01; then +05
+XX	+4315+07657	Asia/Almaty	Kazakhstan (except western areas)
 #
 # +06:30
 XX	+1647+09610	Asia/Yangon	Myanmar; Cocos